问题 多项选择题

下面关于排水明渠表述正确的是()。

A、采用矩形、梯形

B、断面底宽不小于0.3m

C、采用1:0.75-1:1的边坡

D、不能采用自然弧形

答案

参考答案:A, B, C

单项选择题 A1型题
阅读理解

Time Zones(时区)

Strange things happen to time when you travel. Because the earth is divided into twenty-four zones one hour apart(相差).You can have days with more or fewer than twenty-four hours, and weeks more or fewer than seven days.

If you make a five-day trip across the Atlantic Ocean(大西洋),your ship enters a different time zone every day. As you enter each zone, the time changes one hour. Travelling west ,you set your clock back; traveling east , you set it ahead. Each day of your trip has either twenty-five or twenty-three hours.

If you travel by ship across the Pacific(太平洋), you cross the international date line. By agreement, this is the point where a new day begins, when you cross the line, you change your calendar one full time day, backward or forward. Travelling east, today becomes yesterday; traveling west, it is tomorrow.

小题1:Strange things happen to time when you travel because______.

A.no day really has 24 hours

B.the earth is divided into time zones

C.time zones are not all the same size

D.no one knows where time zones are小题2:From this passage it seems true that the Atlantic Ocean___.

A.is divided into five time zones

B.is divided into 24 time zones

C.is in one time zone

D.cannot be crossed in five days小题3:If you cross the ocean going west, you set your clock_____.

A.ahead by 25 hours in a new time zone

B.one hour ahead for the whole trip

C.back one full day for each time zone

D.one hour back in each new time zone小题4:The international date line is the name for______.

A.the beginning of any new time zone

B.the point where a new day ends

C.the point where a new day begins

D.any time zone in the Pacific Ocean