The teacher called Tom to his office because he was caught___in the exam
The researehers delermine what type of plants the virus can infect(感染) and_________insects can carry the virus.
—Did you get my letter? —I received one just as I_________.
.When she called at his studio, she_________that he had gone to Japan.
.Robert made a call to his parents yesterday afternoon. To his disappointment, _________of them answered it.
I_________stop by sometime and thank her for all her help.