问题
It still puzzles today’s scientists_____ some mammals produce their young _____others lay eggs to producetheir offspring (后代)[ ]
A: that; while
B: what; while
C: that; as
D: what; as
B: what; while
C: that; as
D: what; as
正确答案是：
同类题型
ent me the money, ______that I’d do as much for him.
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