Question

【题目】—When did your cousin begin to show his interest in medicine?

—It was a Saturday __________ she noticed her uncle experimenting on a frog in his lab.

A. that

B. what

C. when

D. which

Answer 1

【答案】C

【解析】该定语从句的先行词是a Saturday,关系词在从句中作时间状语，所以用关系副词when。该题考生常误选that ,认为是强调句型。