Every time ______ they met, they would talk several hours together about the persons and things _______ they remembered in the middle school.
| A．that; who | B．when; which |
| C．/; that | D．which; / |
27．At last, the boys found themselves in a pleasant park with trees providing shade and____down to eat their picnic lunch.
| A．to sit | B．sat | C．sitting | D．having sat |
26．The researehers delermine what type of plants the virus can infect(感染) and____insects can carry the virus.
| A．those | B．why | C．which | D．How |
25．—Did you get my letter?
—I received one just as I____.
| A．set out | B．had set out | C．was setting out | D．would set out |
24．When she called at his studio, she____that he had gone to Japan.
| A．is told | B．was told | C．tells | D．Told |
23．Robert made a call to his parents yesterday afternoon. To his disappointment, ____of them answered it.
| A．either | B．both | C．none | D．Neither |