单项选择题
A. as B. when C. until D. if
It is essential that people () enough vitamins every da...
单项选择题It is essential that people () enough vitamins every day.
A. have B. had C. must have D. will have
I'll give you my telephone number in case you () want t...
单项选择题I'll give you my telephone number in case you () want to get in touch with me again.
A. should B. will C. shall D. need