皮皮学,免费搜题
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搜题
【单选题】
妊娠多少胚胎初具人形
A.
4
B.
8
C.
12
D.
16
E.
20
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皮皮学刷刷变学霸
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】青蒿素结构中含有(),具有氧化性,酸性条件下能将碘离子氧化成碘与淀粉指示液显蓝紫色
A.
羰基
B.
过氧桥
C.
酯键
D.
羧基
【简答题】青蒿素结构中含有(),遇碘化钾试液氧化析出(),加淀粉指示剂,立即显()。
【单选题】In this restaurant, there are not enough waiters to wait ______ customers.
A.
on
B.
for
C.
with
D.
to
【单选题】One of the waiters _________ my uncle.
A.
is
B.
are
C.
am
D.
be
【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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