制动阀由自动制动阀和()两部分组成。
A.分配阀
B.三通阀
C.单独制动阀
D.给风阀
参考答案:C
we were all happy _____ 51 gold medals in all in the 29th Olympic Games.
A.to have won
B.to won
C.winning
D. won
早产儿易发生佝偻病,主要是由于()
A.肝肾功能较差
B.胃肠道对维生素D吸收不良
C.胃肠道对钙、磷吸收不良
D.易发生胃肠道功能紊乱
E.体内储钙不足,生长发育快