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问题 单项选择题

青春期龈炎牙龈表现为

A．龋增生．呈细小分叶状
B．跟呈瘤样突起，有蒂、鲜红、质软
C．龋 * * 呈球样增生、质软，多见于前牙唇侧
D．龋退缩、鲜红、质软
E．龋肥大、苍白、质硬

答案

参考答案：C

单项选择题

下列关于队列的叙述中正确的是( )。

A．在队列中只能插入数据

B．在队列中只能删除数据

C．队列是先进先出的线性表

D．队列是先进后出的线性表
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单项选择题

The trip to the Mystery Caves will take place on Sunday, 27 July. You can book your tickets in Room 188 between 2:30 p.m. and 4:00 p.m. every day. Your parents should confirm (确认) the booking by writing to us as soon as possible. You should pay for the trip before 21 July. If we do not receive your money early enough, your booking will be cancelled(取消). If the trip does not take place for any reason, your money will be paid back.
We are planning to meet outside the railway station on Black Street at 8:00 a.m. It will take us about 2 hours to get to the center of the town by train, and from there we have to catch a bus. It will take another hour to get to the Mystery Caves on the bus.
We will spend about 1 hour and a half visiting the caves (山洞), and we hope to catch the 1:30 bus to Happy Lake for some swimming. If we are late, we will have to take the 3:00 bus straight back to Black Street.

If you do not pay for the ticket early enough,
[A] the trip will be cancelled
[B] you can write to Room 188"and pay later
[C] you won’t be able to take the trip
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