Look at these tracks. It be a wolf.It needn't be. It be a fox.A.must; couldB
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Look at these tracks（痕迹）. It ______ be a wolf.It needn't be. It ______ be a fox.
A.must; could
B.may; might
C.need; must
D.could; need
试题答案
A
本题考查情态动词。need作情态动词时不用于肯定句中，因此，首先排除C、D项。对于must的否定回答通常用needn't. could常常表示可能的情况。