15．Time should be made good use of________our lessons well.
| A．to learn | B．learning | C．learn | D．learnt |
Only after the woman had her own child ________ how difficult it was to be a mother.
| A．she realized | B．had she realized |
| C．she had realized | D．did she realize |
Mary, together with his classmates, _____ going to watch the game.
| A．is | B．are | C．will be | D．will |
They went off and left me ______ there all by myself.
| A．sit | B．sat | C．sitting | D．to sit |
The picture is ______ at least twenty pounds.
| A．worthy | B．worth while | C．worthwhile | D．worth |
As we all know, smoking too much can _____ cancer and many other illnesses.
| A．lead to | B．build up | C．result from | D．lie in |