The students _______are hard-working and ready to help should be praised.
| A．who | B．whom | C．which | D．whose |
He was about to tell me the secret ＿＿ someone patted him on the shoulder.
| A．as | B．until | C．while | D．when |
He is the only one of the students who ＿＿ a winner of three years.
| A．is | B．are | C．have been | D．has |
The scientist did ＿＿ experiments to test the new drug.
| A．a series of | B．a good many of | C．a great many | D．a lots of |
These plants are watered ＿＿ .
| A．every a few days | B．every third day |
| C．every others day | D．each two days |
Guilin is ＿＿ worth ＿＿. Have you been to it?
| A．well; visiting | B．well; to visit | C．very; a visit | D．very; a visit |