When ______ comes to research into heart disease and its effects on the body, we do not have adequate substitutes for the use of animals.
| A．it | B．this | C．that | D．which |
Criticism and self-criticism _____ necessary _____ it helps us to correct mistakes.
| A．is, in that | B．are, in that | C．is, in which | D．are, at that |
Robert is said _____ abroad, but I don’t know what country he studied in.
| A．to have studied | B．to study | C．to be studying | D．to have been studying |
The lady said she would buy a gift for her daughter with the _____.
| A．20 dollars remained | B．20 dollars to remain |
| C．remained 20 dollars | D．remaining 20 dollars |
_____ a reply, he decided to write again.
| A．Not receiving | B．receiving not |
| C．Not having received | D．Having not received |
Have you ever stopped _____ how our lie _____ if the world ran out of ol?
| A．to think, would change | B．thinking, would change |
| C．to think, will change | D．thinking, should change |