问题

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:that
B:it
C:this
D:what

正确答案是：

同类题型

_______ you are familiar with the author’s ideas, try reading all the sections as quickly as you can.[ ]

s always full of ideas, butis useful to my knowledge.

_______ my parents’ help, I begin to catch up _______ my classmates

1I really enjoyed your speech,______ there were some parts I didn’t quite understand.

makes this shop different is that it offers more personal services.