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搜题
【单选题】
卧式离心铸造的铸性，其内表面（）A.
质量好
B.
质量差
C.
有缩孔
D.
具有抛物形状
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反馈参考答案：
举一反三
【单选题】关于青蒿素和双氢青蒿素(结构如图)的下列说法，错误的是______。 A．青蒿素的分子式为C15H22O5 B．由青蒿素制备双氢青蒿素的反应属还原反应 C．青蒿素分子中含有过氧链和酯基、醚键 D．双氢青蒿素分子中有2个六元环和2个七元环
A.
正确
B.
正确
C.
正确
D.
三个六袁环和一个七元环
【单选题】The service in this restaurant is very poor there are not enough waiters to wait ______ customers.
A.
on
B.
for
C.
with
D.
to
【单选题】Most of the waiters are____in their work because the owner of the restaurant does not pay them on time.
A.
rack
B.
tack
C.
slack
D.
stack
【单选题】In this restaurant, there are not enough waiters to wait ______ customers.
A.
on
B.
for
C.
with
D.
to
【简答题】已通过()的订阅号，可自动获得自定义菜单
【简答题】[A]visitors[B]owners[C]waiters[D]guests
【单选题】Most of the waiters are ______ in their work because the owner of the restaurant does not pay them on tinge.
A.
rack
B.
tack
C.
slack
D.
stack
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