一、用括号内所给词的正确形式填空。
1. I'll go to the zoo if it ________ (be) sunny tomorrow.
2. Frank ________ (go) to see his grandma if he ________ (be) free tomorrow.
3. If you ________ (work) harder, you will catch up with us soon.
4. I will keep waiting for my friend unless he ________ (ask) me to leave.
5. The students ________ (not plant) trees if it ________ (rain) tomorrow.

1. is 2. will go; is 3. work 4. asks 5. won’t plant; rains

二、从方框中选择适当的连词填空。
whether if although because until before while when so that as soon as
1. ________ I grow up, I will be a nurse and look after the patients.
2. ________ it is fine tomorrow, we will go for a picnic.
3. Alice won't go to bed ________ her mother comes back home.
4. ________ my grandpa is over 80 years old, he still looks strong and healthy.
5. Love your parents ________ they are alive. Don't wait until it is too late.
6. Mike started cooking ________ he got home from school.
7. Before you ask someone for help, find out ________ he is the right person for your problem.
8. —Did you call Michael back?
—I didn't need to, ________ I'll see him tomorrow.
9. It's necessary to divide the waste into different kinds ________ we throw it away.
10. We should take care of the earth ________ we can make a better world to live in.

1. When 2. If / When 3. until 4. Although 5. when / while 6. as soon as / when 7. whether / if 8. because 9. before 10. so that