1. The children eat too much sweet,...they get toothache easily.
a. therefore
b. so
c.but
d. however
2. Hoa missed the bus this morning,... she went to school late.
a.but
b.so
c. however
d. and
3. He didn't go to school yesterday...., he had to ask his friends what they learned then.
a. but
b. Therefore
c. And
d. because
4. The countryside is very peaceful.... the air is so fresh.
a.but
b.or
c.therefore
d.and
5. Mike studied very hard...., he didn't pass the exam.
a. however
b. because
c.and
d.there fore
6.The students volunteer to clean up the local park...there are a lot of used cans and trash there.
a.but
b.because
c.and
d.so
7. Do you live in the country... in the city?
a.or
b.but
c.and
d.there fore
8. She tried hard,...she failed the test.
a.or
b.but
c.and
d.therefore.