551.In warm weather fruit and meat _____ long.
A.don't keep
B.can't be kept
C.are not kept
D.aren't keeping
552.Why did you put the wood near the fire?It's dangerous!
Don't worry.Wet wood won't ____ easily.
A.burn
B.burnt
C.be burnt
D.be burning
551.答案是A;此题中Keep为连系动词后接形容词，不用被动语态，也不用进行时。
552.答案是A;此处说明主语潮湿的木材不易燃这一特性，故burn用主动形式表示被动意义。
