_______cloning human embryos is not legal in many countries, some scientists are already pushing ahead with research in order to produce a cloned human baby.
| A．While | B．When | C．Since | D．if only |
I stopped the car ____ a short break as I was feeling tired.
| A．take | B．taking | C．to take | D．taken |
________ at the cafeteria before, Tina didn’t want to eat there again.
| A．Having eaten | B．To eat | C．Eat | D．Eating |
If _____ to look after luggage for someone else, inform the police at once.
| A．asked | B．to ask | C．asking | D．having asked |
The sun began to rise in the sky, ________ the mountain in golden light.
| A．bathed | B．bathing | C．to have bathed | D．have bathed |
You cannot accept an opinion ________ to you unless it is based on facts.
| A．offering | B．to offer | C．having offered | D．offered |