灭火消防车、供水消防车和通讯指挥消防车，凡服役年数满（）年，必须退役。
A、6
B、8
C、10
D、12
参考答案：D
颌内静脉汇入（）
A.翼丛
B.面前静脉
C.面后静脉
D.面总静脉
E.颌外静脉
. The actor_____the children with all kinds of tricks, which they ___very much
A．entertained; entertained
B．entertained; enjoyed
C．enjoyed; entertained
D．enjoyed;enjoyed
