问题
选择题
________ it comes to the increasing use of motor vehicles in the cities，some people think it should be limited．
A．Because
B．Once
C．When
D．While
答案
答案：C
搜题请搜索小程序“爱下问搜题”
________ it comes to the increasing use of motor vehicles in the cities，some people think it should be limited．
A．Because
B．Once
C．When
D．While
答案：C