Last month, the Japanese government expressed their thanks for the air they_______ from China.

A．receive

B．are receiving

C．have received

D．had received

系统用户离职或离任后，应及时移除系统角色。如需保留系统用户，最长不超过（）。

A、三个月

B、二个月

C、一个月

D、十天