—What do you think of being a volunteer, John?—I find it a stressful job but one ___ you can really help people.
. I'd really appreciate ________ if you would turn off the lights before you leave.
It never _____ humans until the mid1990s that some animals can be cloned.
If you _____ his wife’s income____ his own,the total of their income _____ 3000 yuan.
Is it a wonder that ____little cells can store much energy?
As a senior high student, you should your energy on how to master the skills of learning.