_______ the dolphin lives in the sea, it is not a fish; it is a mammal.

_______, he has to be very careful about what he eats.

_______ he made an excellent speech in defense of his friend, everyone admired and respected him.

_______, we could not clearly understand him.

Lucy _______ her foot if she had not dropped the old box.

_______ her support, we _______ these things.

I will lend you the dictionary _______ you will return it tomorrow.

If it _______ an hour ago, the streets _______ wet now.

There were _______ last weekend.

He is _______ man I have ever met.

You are _______ I think you are.

_______ an object from the surface of the Earth, _______ it weighs.

I am always meeting her _______

Some students left the room _______

I have not contacted Jacky _______ for London.

David rushed to the scene _______ he heard the news.

Let’s go the Oxford Street, _______ there are plenty of fashion shops.

A man _______ shouted angrily.

Professor Chan gave the student the book _______ last year.

_______ is none of your business.

Is it true _______?

He told me _______ at the scene of the accident.

Her doctor advised her to do jogging because she is _______

John did not want to be so _______, but he could not help it.

Frequent practice _______ you to get _______ in learning a language.

They have ever advised _______ the hotel for reservation.

John _______ him my phone number.

“_______,” the mother warned her sons.

_______ the problem.

Cho đa thức \[{\rm{4}}{{\rm{x}}^{\rm{5}}}{{\rm{y}}^{\rm{2}}} - {\rm{5}}{{\rm{x}}^{\rm{3}}}{\rm{y}} + {\rm{7}}{{\rm{x}}^{\rm{3}}}{\rm{y}} + {\rm{2a}}{{\rm{x}}^{\rm{5}}}{{\rm{y}}^{\rm{2}}}\]. Tìm a để bậc đa thức bằng 4.