皮皮学，免费搜题
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【单选题】
国家实行危险化学品登记制度，要求危险化学品（）应当向危险化学品登记机构办理登记。A.
生产企业和经营企业
B.
生产企业和储存企业
C.
生产企业和进口企业
拍照语音搜题，微信中搜索"皮皮学"使用
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知识点：
皮皮学刷刷变学霸
举一反三
【单选题】—When you have difficulty , do remember to_________. Two heads are better than one.
A.
give up
B.
ask for help
C.
make a decision
D.
try your best
【简答题】有人认为公钥加密比常规加密更安全,对不对?
【单选题】如图所示电路，若以 A 点作为参考点， X 点的电位为 5 V ；若以 B 点为参考点， X 点的电位为 10 V ，则 U AB = （ ） 。
A.
5V
B.
10V
C.
15V
D.
20V
【单选题】—What do you think of the two students ________ to take part in the competition? —They are hardworking as well as intelligent.
A.
selecting
B.
selected
C.
having selected
D.
to select
【简答题】Do you know what lungs (肺) are like? (11) are in the upper part of our bodies. We have two of them. There are thousands of little pipes (管子) going through them. The (12) are like the branches of a tre...
【简答题】若电路中 A点的对地电位是 15 V,B点的对地电位是 20 V,则U BA =________ 。
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