阅读理解。

      Linda and Mary are good friends. Linda is thirteen. She comes from the U.S.A. Mary is twelve. She’s from London(伦敦). They study in the same school, but in different classes. Linda’s father teaches English in a middle school. Her mother drives a car. Mary’s mother works in an office. Her father is a doctor. Linda can speak English, French(法语) and a little Chinese. Linda’s mother likes cooking. She likes eating rice. But Linda’ s father doesn’t. He likes drinking milk and eating bread. Mary’s mother doesn’t like cooking. But she likes doing some shopping. She can make nice skirts and dresses. Mary’s father likes doing housework(家务).

根据短文内容，回答下列问题。

1. Where does Mary come from?

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2. What does Linda’s father do?

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3. Where does Mary’s father work?

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4. What can Linda speak?

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5. What does Mary’s mother do?

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当左心室舒张时（）

A.三尖瓣开放 

B.三尖瓣关闭 

C.二尖瓣开放 

D.二尖瓣关闭 

E.各静脉口开放