质量为50 kg的乘客乘坐电梯从一层到四层，电梯自一层启动向上做匀加速运动，加速度的大小是1 m/s²，则电梯启动时地板对乘客的支持力为（g取10 m/s²）（   ）

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阅读短文, 下列问题

Miss Han: You bring(带来) many things to school, Kevin. Can you tell (告诉) me what are on your desk?

Kevin: Yes, I can. There is an eraser,a ruler, three pencils and a pencil box on my desk.

Miss Han: What is in your drawer(抽屉)?

Kevin: In my drawer, there are two books and a notebook.

Miss Han: What is that on the floor?

Kevin: It is my school bag.

Miss Han: Do you bring your lunch box(饭盒) to school?

Kevin: Yes, I do.

Miss Han: Where do you put it?

Kevin: I put it under my desk.

25×4=____    12×5=____    125×8=____    24×5=____