问题
选择题
Every student is required to watch the teacher carefully before ___ the chemistry experiment.
A．performing
B．taking
C．picking
D．having
答案
答案：A
本题考查动词辨析。句意为：在操作化学实验之前，每个学生 必须认真观察教师的示范动作。perform表演；操作。
搜题请搜索小程序“爱下问搜题”