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
下列划线词的词性和用法都与例句相同的一项是（ ）例句：项伯杀人，臣活之
Sunglasses are used ________ protecting your eyes in sunny days.
32．—Why are you so sweaty? — I__________football with my classmates and how I want to have a drink!
Some more milk, please. —-Sorry, there’s ________ left in the fridge.
Would you like some more chicken?——No, thanks I am ______ a diet and try to _____ weight