Brain, like muscles, also needs some kind of exercise and nutrition. The more you use your brain in the right direction, the more you ________ enhance your ability.
A．could B．might
C．shall D．will
We all know that we ________ our carbon footprint, but I suspect that many people wouldn't be prepared to go as far as Joan Pick, a retired scientist living in south London.
A．must have reduced B．should have reduced
C．may have reduced D．could have reduced
No matter how healthy you ________ be, you need to consult a doctor from time to time.
A．should B．will
C．must D．may
—May I smoke here?
—If you ________， choose a seat in the smoking section.
A．should B．could
C．must D．may
We can't use it to tie the goods because it ________ be broken at the weakest position.
A．shall B．may
C．can D．would
If the island ________ a tourist attraction, last week's earthquake would have caused far more deaths.
A．remained B．would remain
C．has remained D．is to remain
