Question

【题目】Scientists now say that five seconds is all that _______ takes for food to become contaminated with enough bacteria to make you sick.

A. it B. one C. that D. this

Answer 1

【答案】A

【解析】

试题分析：句意：……食物发生菌变使人生病需要5秒钟。it在本句中作形式主语，真正的主语为后面的动词不定式结构“to become contaminated with enough bacteria to make you sick”。故选A项。