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问题 选择题
已知函数f（x）=
3
sinwx+coswx（w＞0），y=f（x）的图象与直线y=2的两个相邻交点的距离等于π，则f（x）的单调递增区间是（　　）
A．[kπ-
π
12
，kπ+
5π
12
]，k∈Z		B．[kπ+
5π
12
，kπ+
11π
12
]，k∈Z
C．[kπ-
π
3
，kπ+
π
6
]，k∈Z		D．[kπ+
π
6
，kπ+
2π
3
]，k∈Z
答案

f（x）=

3
sinwx+coswx=2sin（wx+
π
6
），（w＞0）．

∵f（x）的图象与直线y=2的两个相邻交点的距离等于π，恰好是f（x）的一个周期，

∴

2π
w
=π，w=2．f（x）=2sin（2x+
π
6
）．

故其单调增区间应满足2kπ-

π
2
≤2x+
π
6
≤2kπ+
π
2
，k∈Z．kπ-
π
3
≤x≤kπ+
π
6
，

故选C．

填空题

阅读下面的短文，根据上下文意义和所给单词首字母，写出空白处单词的正确形式。

    If you travel by (1)a             across the center of Africa or South America, you fly over forests for

thousands of kilometers. These great forests are the oceans of (2)t             . There are thousands and

thousands of kinds of plants and (3)a            .

    However, the world's forests are getting (4)s             all the time. In many places, we're cutting down

the trees because we need wood and we need more farmland. Some people say that (5)t              will not

be any forest like these in 30 years. What will happen if they (6)d             ?

    If we cut down our forests, a lot of plants and animals will disappear from the (7)w             . In a lot

of places the new farmland will soon look like the old desert. Crops will not grow there. It will not rain

very often, and the weather will get very hot. Perhaps the climate (气候) of the world will (8)c             .

This will be (9)d             for everyone in the world. That's (10)w              we must take care of our forests.

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多项选择题

在V面和H面上投影均为矩形的空间物体，可能是（）。

A.长方体

B.三棱柱

C.圆柱体

D.三棱锥

E.四棱锥
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