题干

下列运动中,最接近匀速直线运动的是(   )

A:奥运会上百米赛跑

B:游乐场里飞速旋转的过山车

C:站在商场的自动扶梯上上楼的顾客

D:从滑梯上下滑的小朋友

上一题 下一题 0.0难度 选择题 更新时间:2018-07-16 06:07:33

答案(点此获取答案解析)

C

同类题3

玉米植株的雄花着生在植株的顶端,雌花着生在植株的叶腋。玉米植株一般是雌雄同株异花,也出现只开雄花或只开雌花的雄株或雌株。玉米植株的性别决定受两对等位基因(B和b、T和t)控制,这两对等位基因位于两对同源染色体上。玉米植株的性别与基因型的对应关系如下表。下列叙述中,不正确的是
基因型
B和T同时存在
(B_T_)
T存,B不存在
(bbT_)
T不存在
(B_ tt或bbtt)
性别
雌雄同株异花
雄株
雌株

同类题4

完形填空

    Years ago, I lost my sight completely. I would do anything for a 1 . In fact, desperate and 2 , I tried every supplement, experimental trial, diet and anything anyone 3 . All for nothing.

    But now, after 25 years in physical darkness, my life is 4 than ever. The change began one day, many years ago, when I drank my tea 5 , swallowing gulps(一大口) of “poor me” and wondering what my future would 6 . Then, the doorbell rang. Janet came in and brought an idea. “Have you ever thought about working as a(n) 7 ? ” she said, “You speak Spanish. Go for it.”

    Her idea 8 me to make a phone call. And the interpreting company I contacted invited me to take a test. Thank goodness it was 9 .

    “We're so 10 with the results,” the receptionist said the next day, “that we want to send you on your first 11 tomorrow. It's in the Immigration and Naturalization Court.”

    That was the beginning. That was when I began to 12 possibilities when my blindness wouldn't get 13 . The view of my world had changed. Blindness didn't have to label me as

    14 . On the contrary, the blindness improved my ability to 15 information and present a quicker and more 16 interpretation.

    The letters from judges, praising me for my work, 17 me for the hours I'd spent studying, memorizing, and 18 .

    Blindness? Not a barrier any more. 19 , it became a handy 20 to sharpen my creativity. Not only in the courtroom, but at home, in my relationships and in the way I viewed myself.