皮皮学，免费搜题
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搜题
【单选题】
设 则下列结论正确的是A.
处处可导
B.
处处不可导
C.
仅有一点可导
D.
在有理点处均可导
拍照语音搜题，微信中搜索"皮皮学"使用
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参考解析：
知识点：
皮皮学刷刷变学霸
举一反三
【单选题】Mr Black decided to give up his farm and devote all his time to______ those children living on the streets.
A.
help
B.
helping
C.
be helping
D.
being helped
【单选题】Who was Jack?
A.
Alice's son.
B.
Mr Davis' boss.
C.
Alice's brother.
D.
Alice's husband.