Cho hình chóp S.ABC có đáy ABC là tam giác vuông cân tại A với AB =AC=a. Biết tam giác SAB đều nằm trong mặt phẳng vuông góc với mặt phẳng ABC. Tính thể tích hình chóp S.ABC?

Cho hình chóp S.ABC có đáy ABC là tam giác vuông cân tại A với AB =AC=a. Biết tam giác SAB đều nằm trong mặt phẳng vuông góc với mặt phẳng ABC. Tính thể tích hình chóp S.ABC?

Cho hình chóp S.ABC có đáy ABC là tam giác vuông cân tại A với AB =AC=a. Biết tam giác SAB đều nằm trong mặt phẳng vuông góc với mặt phẳng ABC. Tính thể tích hình chóp S.ABC?

  You needn't have done this work.

A.  It's not necessary for you to do this work.

B.  You have done this work that I don't need.

C.  There's no need for you to do this work.

 Nam is twenty years old. His brother is ten.

A.  Nam is older than his brother two times.

B.  Nam is twice as old as his brother.

C.  His brother is twice as young than Nam.

D.  Nam is two times as older as his brother.

   They               for more than 2 hours but they didn't stop to rest.

A.  had been playing                                    B. were playing

C. have been playing                                  D. have played

  You'll have to wait at the bus stop           the bus comes.

A.  before               B. after                           C. while                D. until

   I'd rather you             in the class.

A.  not talk            B. didn't talk                  C. don't talk         D. aren't talked

 Only because he had to support his family                  to leave school early.

A .did Jim decide                                            B. does Jim decide

C. that Jim decides                                     D. Jim decided

 The story was so funny that I couldn't help laughing.

A.  I couldn't laugh because the story was so funny.

B.  I couldn't help you laugh because the story was so funny.

C.  The story was so funny for me to laugh.

93.            I'd rather stay at home than go out with her.

A.  I'd better stay at home than go out with her.

B.  I'd prefer to stay at home to going out with her.

C.  I don't want to go out with her so I choose to stay at home.

D.  I decide to stay at home instead going out with her.

          it was cold, she didn't wear a coat.

A. Because           B. Although                             C. Because of       D. In spite of

Do you mind if I              a photo here?

She is sleeping now                 she worked very hard yesterday.

 "I didn't steal your bag", Ha said

A.  Ha refused to steal my bag.

B.  Ha denied stealing my bag.

C.  Ha admitted stealing my bag.

 I wish I had gone there with my brother.

A.  I hadn't gone there with my brother which made me feel uncomfortable.

B.   I regret not having gone there with my brother.

C.  If only I went there with my brother.

 If it hadn't been for his carelessness, he would have passed the exam.

A.  He was careless because he hadn't passed the exam.

B.  If he was more careful, he would pass the exam.

C.  If he had been more careful, he would have passed the exam.

Công thức cấu tạo C4H10 có mấy

Để loại bỏ khí etilen có lẫn trong metan ta có thể làm gì

Để chứng minh sản phẩm cháy của metan có CO2 ta làm gì

 Lan tried her best to pass the exam            satisfy her parents.

A.  in order to                                     B. so that she

Tính chất vật lý của benzen

ở ruồi giấm alen A quy định tính trạng thân xám trội hoàn toàn so với a quy định thân đen.cho các con ruồi giấm cái thân xám giao phối ngẫu nhiên với các ruồi giấm đực thân đen ,đời F1 thu đc tỉ lệ kiểu hình 7 xám : 1 đen.

a) giải thích kết quả và viết sơ đồ lai từ P đến F2

 Mai's score on the test is the highest in the class. She           hard yesterday.

A.  must have studied                         B. should have studied

Chất có lk đôi dễ dàng tham gia loại phản ứng nào

  Neither Nam or his sisters                 listening to pop music.

   Tim, along with his friends,             going to the party.

A.  is                      B. are                   C. has                   D. have

  We got used              on the left hand side after a year.

A.  to traveling                                   B. to travel

  When I was young, I             fishing every afternoon.

A.  was used to go                              B. used to go

C. used to going                                D. used to be going

Nga seemed to have an enjoyable day last week,            ?

A.  Did she            B. hadn't she        C. didn't she         D. hasn't she

          high school, Nam went abroad to study in the UK.

A. After finished                               B. He was finished

C. Having finished                            D. Having been finished

 Rarely has a 12- year - old made so much money.

A.  12 - year-olds rarely make money.

B.  A 12 -year-old rarely makes lots of money.

C.  A 12- year-old has seldom made so much money.

D.  A 12- year- old has never made that much money.

  John is my boyfriend. I borrowed his book last night.

A.  John, whose book I lent last night, is my boyfriend.

B.  John, whose book I borrow last night is my boyfriend.

C.  John, who is my boyfriend, borrowed my book last night.

D.  John, whose book I borrowed last night, is my boyfriend.

  I wish I had studied hard last year.

A.  I wish to study hard last year.

B.  I didn't study hard last year.

C.  I had studied harder than I used to.

 Don't forget              a letter when you arrive there.

A.  to write            B. writing             C. to writing         D. write

 She advised me              the course.

A.  not to take                                    B. to not take

C. not taking                                     D. not to taking

  I used to live in the country                 people are very friendly.

A.  which               B. which in           C. where               D. in that

     Let's do some sightseeing.

A.  He suggests doing some sightseeing.

B.  He says we can do some sightseeing.

C.  He allows us to do some shopping.

D.  He agrees to do some shopping with her.

   The sooner you stop smoking, the better you feel.

A.  As soon as you feel better, stop smoking.

B.  When you stop smoking, you'll begin to feel better.

C.  You've stopped smoking so you feel better.

D.   If you stop to smoke sooner, you'll feel worse.

"Why didn't you go out with him?" Mai said

A.  Mai asked me why I didn't go out with him.

B.  Mai asked for the reason I had gone out with him.

C.  Mai wanted to know why I hadn't gone out with him.