It________heavily for 2 weeks and the farmers were very worried.
A．has been raining B．had been raining
C．has rained D．had been rained
You cannot tell________looking at someone whether or not he has HIV.
A．without B．by
C．for D．with
The days are gone________you can breathe fresh，unpolluted air or drink clean, unpolluted water in the countryside.
A．when B．that
C．where D．which
Learn some relaxation exercises and do them every time you feel________.
A．embarrassed B．stressed
C．ashamed D．impressed
Many young people don't work hard, and regret it later when the opportunity is gone.They only realize it________it is too late.
A．when B．before
C．in case D．until
Everybody needs calcium, but it is quite possible for a similar person to be totally healthy by eating only________.
A．as half much B．as much half
C．half as much as D．half as much
