下列说法不正确的是（） A．人推木箱未动，这时地面对木箱_爱下问搜题

搜题请搜索小程序“爱下问搜题”

问题选择题

下列说法不正确的是（　　）

A．人推木箱未动，这时地面对木箱的摩擦力等于人的推力

B．木箱受到的重力与地面对木箱的支持力是一对平衡力

C．在木箱下面垫上几根圆木再推，是为了减小摩擦力

D．木箱运动时有惯性，静止时没有惯性

答案

A、木箱处于静止状态，木箱在水平方向上受到的摩擦力和推力就是一对平衡力；

B、木箱受到的重力与地面对木箱的支持力是竖直方向上的一对平衡力；

C、在木箱下面垫上几根圆木用滚动代替了滑动，减小了摩擦力；

D、木箱运动和静止时都具有惯性．

故选D．

单项选择题

首先应做的检查是

A．X线腹部平片

B．血常规化验

C．腹部B超

D．腹腔穿刺

E．膜部CT

完形填空

The Price of a Dream
I grew up poor, living with my wonderful mother. We had little money but plenty of love and attention. I was   36  and energetic. I understood that no matter how poor a person was, he could still   37  a dream.
My dream was to be a sportsman.   38  I was sixteen, I had started playing baseball. I could throw a ninety-mile-per-hour fastball and hit anything that moved on the football field. I was also   39 . My high-school coach was Ollie Jarvis, who not only believed in me, but taught me 40 to believe in myself. He   41 me the difference between having a dream and realizing the dream. One particular   42  with Coach Jarvis changed my life forever.
It was the summer between my junior and senior years, and a friend recommended (推荐) me for a summer job. This meant a chance for money in my pocket—money for a new bike and new clothes, and the   43  of savings for a house for my mother. Then I realized I would have to   44  summer baseball to deal with the work schedule, and that meant I would have to tell Coach Jarvis I wouldn’t be playing.
When I told Coach Jarvis, he was as   45  as I expected him to be. “You have your whole life to work,” he said. “Your playing days are limited. You can’t   46  to waste them.” I stood before him with my head hanging, trying to think of the   47  that would explain   48  him why my dream of buying my mom a house and having money in my pocket was worth facing his   49  in me.
“How much are you going to make at this job, son?” he asked. “Three twenty-five an hour,” I replied.
“Well,” he asked, “is $3.25 an hour the   50  of a dream?”
That simple question made it   51  to me the difference between   52  something right now and following a dream. I   53  myself to sports that summer, and within the year I was   54  by the Pittsburgh Pirates to play baseball, and was   55  a $20,000 contract. In 2000, I bought my mother the house of my dream!

A．By the time

C．At one time

C．hopelessness

D．disappointment