如图所示，物体M静止于倾斜的木板上，当倾角θ由00缓慢增大，直至M开始滑动之前的过程中，下列说法正确的是（ ）
A．物体对木板的压力逐渐减小
B．物体所受的支持力和摩擦力都减小
C．物体所受支持力和摩擦力的合力不变
D．物体所受重力、支持力和摩擦力这三个力的合力逐渐增大
AC
以物体为研究对象手重力支持力和摩擦力，合力为0.D错。支持力和摩擦力合力与重力等大反向，C对。将重力沿木板，垂直木板分解
，倾角变大，摩擦力变大，支持力变小，A对B错。
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| I live in a big city with a lot of homeless people. Luckily there're small ways of helping them and you needn't have a lot of __1__. One way to help is to buy their monthly magazine. By doing this one day, I got to __2__ a young homeless man. He was often __3__ the magazine at the train station. He was a poor farmer from another country. After a while, I discovered that his __4__ was close to mine. It meant that we were born in the same month. I met him last year __5__ after his birthday, and after congratulating(祝贺) him, without thinking, I asked if he had had a good day. He __6__ and said that he hadn't really celebrated. I felt so __7__. I just couldn't bear the thought of this nice, young man being __8__ on his 25th birthday with no presents, no cake, nothing! So I went home and looked in my yarn(纱线) basket. __9__ for me, I had enough yarn __10__. I set to work and knitted(编织) a __11__ for the young man. The yarn had become a little dirty because I didn't knit very often. Then I washed the yarn so the scarf would be __12__ when he got it. I met him on my own birthday as I was going shopping. I had hoped to meet him so I had__13__ the scarf and a piece of my own birthday __14__ around with me. He was very happy with these gifts and so was I. The __15__ in his eyes was the best present he could have given me! | ||||
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