![](https://lstatic.shangxueba.com/sxbzda/h5/images/m_q_title.png)
You ______ a tip if you're not satisfied with the service.A.mustn't leaveB.must leaveC.can
You ______ a tip if you're not satisfied with the service.
A.mustn't leave
B.must leave
C.can leave
D.don't have to leave
![](https://lstatic.shangxueba.com/sxbzda/h5/images/tips_org.png)
You ______ a tip if you're not satisfied with the service.
A.mustn't leave
B.must leave
C.can leave
D.don't have to leave
第2题
孕妇在妊娠期会发生一系列的生理变化,以下关于消化系统的描述,不正确的是
A.妊娠早期,约50%的妇女出现早孕反应,于妊娠12周左右自行消失
B.牙龈充血、水肿、增生,牙齿易松动及出现龋齿
C.孕妇常有唾液增多
D.胃排空时间缩短,常有饥饿感
E.肠蠕动减弱,易便秘
第7题
胎儿期,随孕周增加,其血液系统、循环系统及呼吸、消化系统均会发生相应变化。
妊娠8周以后,胎儿血循环出现哪种细胞,形成防止细菌感染的第一道防线
A.粒细胞
B.红细胞
C.单核细胞
D.淋巴细胞
E.白细胞
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