The children remembered to ______ themselves at first, but things went out of control minutes later.
27.At last, the boys found themselves in a pleasant park with trees providing shade and____down to eat their picnic lunch.
26.The researehers delermine what type of plants the virus can infect(感染) and____insects can carry the virus.
25.—Did you get my letter? —I received one just as I____.
24.When she called at his studio, she____that he had gone to Japan.
23.Robert made a call to his parents yesterday afternoon. To his disappointment, ____of them answered it.