If this product does not give you complete satisfaction, please return it to the manufacturer, stating when it ________.
| A．is purchased | B．will be purchased |
| C．purchases | D．has purchased |
_____ makes this shop different is that it offers more personal service.
| A．What | B．That | C．Which | D．Why |
No one has yet succeeded in solving the _____ of how life first began.
| A．biology | B．gravity | C．puzzle | D．theory |
_______ his sister, Jack is quiet, and does not easily make friends.
| A．Dislike | B．Unlike | C．Along with | D．As to |
. The television station reported several times to _________ drivers parking their cars on the blind road.
| A．prevent | B．keep | C．forbid | D．protect |
——Can I smoke here? ——Sorry. We don’t allow _______here.
| A．people smoking | B．people smoke | C．to smoke | D．smoking |