____ has helped to protect the environment is worth praising.
| A．Who | B．The one |
| C．Anyone | D．Whoever |
“Was his father very strict with him when he was at school?” “Yes. He had never praised him _______ he became one of the top students in his grade.”
| A．after | B．unless |
| C．until | D．when |
You will succeed in the end ____ you give up halfway.
| A．even if | B．as though |
| C．as long as | D．unless |
Not until I began to work ________ how much time I had wasted.
| A．didn’t I realize | B．did I realize | C．I didn’t realize | D．I realize |
Not a single song ________ at yesterday’s party.
| A．she sang | B．sang she | C．did she sing | D．she did sing |
I finally got the job I dreamed about. Never in all my life ________ so happy!
| A．did I feel | B．I felt | C．I had felt | D．had I felt |