跳伞运动员从高空下落时,在他张伞后作匀速直线运动,则下列说法正确的是 [ ] A

题型:选择题

问题:

跳伞运动员从高空下落时,在他张伞后作匀速直线运动,则下列说法正确的是 [ ]

A.动能、重力势能都不变

B.重力势能减少,动能增加

C.重力势能减少,动能不变

D.重力势能不变,动能为零

考点:动能大小的比较势能大小的比较
题型:选择题

关于人类的起源,现在普遍认同的观点是人类起源于(  )

A.亚洲

B.欧洲

C.美洲

D.非洲

题型:选择题

Have you ever thought about what you would like to do after school? Perhaps one of these rather different jobs will suit you.

TASTER: Food companies need people to taste the products that they are making. So many kinds of no bad-tasting food are put onto the supermarket shelves. All tasters do all day is take small bites of food. They make notes of what tastes good and what tastes bad. It is not a job for those who would like to stay thin.

SNAKE MILKER: This involves taking the poison out of a snake’s teeth. You hold the snake over a glass and make it open its mouth very wide. The poison will then drip from the back of the teeth into the glass; this is known as milking the snake. You have to be very brave if you want to try this.

GOLF BALL HUNTER: You will spend your day diving into waterholes at different golf courses to hunt for lost golf balls. You could be picking up as many as 5,000 balls a day. Many golfers are willing to buy used golf balls and you could be making a lot of money.

CLOCK CLEANER: Every day you will be climbing to the top of the clock towers in the city. Your responsibilities will be to oil, wind and repair the clocks. This is not a job for someone who is afraid of heights.

小题1: If you are a taster, you will          .

A.pick up golf balls

B.oil and repair the clocks

C.get some milk from snakes

D.try different kinds of food小题2: If you are afraid of heights, you’d better not choose the job as a          .

A.taster

B.snake milker

C.clock cleaner

D.golf ball hunter小题3: You can probably find this passage in a          .

A.newspaper

B.textbook

C.report

D.novel

题型:选择题

γ运动神经元在牵张反射中的作用是

A.直接诱发梭外肌的收缩
B.直接发动牵张反射
C.引起腱器官兴奋
D.使肌梭感受器处于敏感状态

题型:选择题

下图是人体甲状腺细胞摄取原料合成甲状腺球蛋白的基本过程,试回答([()]中填序号,()内填写名称)

用含18O标记的氨基酸培养上图细胞,则出现18O的部位依次为()(用图中序号回答)。甲状腺球蛋白合成过程体现了生物膜()。

题型:选择题

一个完整的程序由()、程序的内容和程序结束三部分构成。

A、工件名称

B、程序号

C、工件编号

D、地址码

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