变直径管直径由L00MM扩大到200MM直径变大后的流速为L．5M/S直径变化前的流速为（）M/S

如图6—5所示，垂直放置的矩形平板挡水，水深3m，静水总压力P的作用点到水面的距离yD为（　　）m。

A．1.25
B．1.5
C．2
D．2.5

理想流体是( )。

A．无黏性流体
B．不可压缩流体
C．符合牛顿内摩擦定律的流体
D．静止的流体

按第三强度理论计算如图5-58所示单元体的相当应力σr3是（　　）MPa。

A．20
B．30
C．60
D．50

84.__________

Does Tom know any other foreign languages __________English

A．but
B．except
C．besides
D．beside

-- Never'thought to see you here.
--__________

A．So did I.
B．Oh, haven' t you
C．It' s a small world.
D．I' m well. Thank you. And you

--She asked you when_________ again
--Tell her that I'LL let her know when he

A．he came; comes
B．would he come; will come
C．he came; will come
D．he would come; comes

回答题
Here is a poster on a middle school website.
Going, Going, Gone!
The Haynes Middle School Parent Teacher Organization
invites you to attend our latest fund(基金)-raiser,
The Fourth Annual Haynes School Auction(拍卖) !
Saturday, May 10
6:00 p. m.--11:00 p. m.
in the school hall
6:00 p. m. --6:30 p. m. : All items for auction are previewed.
6:30 p. m. --7:00 p. m. : Silent auction begins.
7:00 p. m.--7:30 p. m. : Highest bidders (出价人) from silent auction are determined.
7: 30 p. m. --11:00 p. m. : Main auction begins.
Items up for bids in the silent auction range in value from $ 5.00 to $ 30.00.
Items up for bids in the main auction include the following:
Airline tickets to a place of your choice
Weekend getaways at firstclass hotels
Season tickets to the Chicago Bears football game
$ 50 gift tickets to local gift shops, restaurants, and salons
Theater tickets to The Merchant of Ve.nice
Don't miss the boat! Book your tickets today. Last year, tickets sold out in five days! Tickets are sold on a first-come, first-served basis. $15.00 per person. All the money from the auction will be given to the Haynes School computer laboratory.
Which of the following is NOT mentioned as being up for bid at the auction

A．A movie pass to the local cinema.
B．A weekend stay at a hotel.
C．A ticket to a restaurant.
D．Airline tickets.