问题 选择题

一物体在A、B两点的正中间由静止开始运动(设不会超越A、B),其加速度随时间变化如图所示。设向A的加速度为为正方向,若从出发开始计时,则物体的运动情况是( )

A 先向A ,后向B,再向A,又向B,4秒末静止在原处

B 先向A ,后向B,再向A,又向B,4秒末静止在偏向A的某点

C 先向A ,后向B,再向A,又向B,4秒末静止在偏向B的某点

D 一直向A运动,4秒末静止在偏向A的某点

答案

答案:D

根据a-t图象作出其v-t图象,如右图所示,

由该图可以看出物体的速度时大时小,但方向始终不变,

一直向A运动,又因v-t图象与t轴所围“面积”数值上

等于物体在t时间内的位移大小,所以4秒末物体距A点为

2米

阅读理解

Japanese scientists have taken the first photographs of one of the most mysterious creatures in the deep ocean — the giant squid.

Until now the only information about the behavior of the creatures which measure up to 18 meters (59 feet) in length has been based on dead or dying squid washed up on shore or capturedin commercial fishing nets.

But Tsunemi Kubodera, of the National Science Museum, and Kyoichi Mori of the Ogasawara Whale Watching Association, both in Tokyo have captured the first images of Architeuthis attacking bait900 meters below the surface in the cold, dark waters of the North Pacific. “We show the first wild images of a giant squid in its natural environment,” they said in a report in the journal Proceedings B of the Royal Society.

Little is known about the creatures because it has been so difficult to locate and study them alive. Large ships and specialist equipment, which is costly, are needed to study deep sea environments.

The Japanese scientists found the squid by following sperm whales, the most effective hunters of giant squid, as they gathered to feed between September and December in the deep waters off the coast of the Ogasawara Islands in the North Pacific. They used a remote long-line camera and depth logging system to capture the giant squid in the ocean depths.

The most dramatic character of giant squids is the pair of extremely long tentacles, distinct from the eight shorter arms. The long tentacles make up to two-thirds of the length of the dead specimensto date. The giant squid appear to be a much more active meat-eating animals than researchers had thought.

Notes:

① squid  n. 鱿鱼

② capture  vt. 捕获

①    bait  n. 鱼饵

②    tentacle  n. 触角,触须

③    specimen  n. 标本,样本

小题1:The passage mainly tells us that ________.

A.Scientists captured a giant squid alive

B.Scientists captured a giant squid on camera

C.giant squids are special meat-eating animals

D.giant squids mainly live in the deep sea小题2:According to the passage, we can infer that the word “Architeuthis” should refer to ________.

A.a scientist

B.the sperm whale

C.a big ship

D.the giant squid小题3:Which of the following about giant squids is TRUE?

A.They like living the cold and deep waters.

B.They mainly feed on the dead fish.

C.They like playing, using their tentacles.

D.They have only eight arms around the mouth.小题4:According to the passage, the scientists located the giant squid ________.

A.through a remote long-line camera

B.by using depth logging system

C.by following sperm whales

D.by using the bait to attract them

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