It was years _____ I had visited my hometown in Dalian, Liaoning Province.
| A．after | B．that | C．since | D．when |
The black baby boy is at the stagehe can only say a few simple words but not yet full sentences．
| A．when | B．where | C．which | D．why |
Up to now, no one has come up with a（n）explanation of why dinosaurs died out, and it remains a mystery．
| A．astonishing | B．amusing | C．convincing | D．puzzling |
All the cloned animals have so far suffered from some serious disorders, many ofdying soon after birth．
| A．that | B．whom | C．which | D．them ． |
Your IQ isn’t _____determines whether you will succeed in your future life.
| A．what | B．where | C．that | D．why |
Housing prices _____much higher now if the government hadn’t taken measures to control house dealing.
| A．were | B．would be | C．had been | D．would have been |