Một thanh chắn OA đồng chất tiết diện đều có trọng lượng 180 N đầu O của Thanh được gắn vào tường bằng một bản lề còn đầu A được giữ bằng một lực F thẳng đứng hướng lên như hình vẽ tính độ lớn của lực F tác dụng lên thanh để thanh cân bằng nằm ngang.

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Bài 1: Complete the sentences with the correct prepositions: 1,That singer has become very popular..................the youth 2,Your profession is similar.............mine 3,My home is far................school 4,My classmates are interested...............watching Spiderman 5, Dong Ho painting are made............traditional paper with beautiful natural colour 6, Mai is very good.................drawing 7, I'll phone you................Tuesday morning..................10 o'clock, ok? 8, She spends all her money..............clothes 9, We went by car and children went.......................foot 10, I am looking................my hat. I can't find it anywhere Bai2: Rewrite the sentences using the words given: 1, Peter started to collect stamps two years ago Peter has...................................... 2, I read books every day. I want to widen my knowledge I want........................................ 3,Mark is the tallest boy in his class No one......................................... 4, I'm interested in playing sports I find........................................... 5, The furniture was so expensive that I didn't buy it. The furniture was too.................................... Bai3: Put the verbs in brackets into the correct form: 1, .........................your father (play)..............football next summer? 2, Kate (love)................dolls but she says she ( not continue)...............this hobby in the future 3, I (have)...............a cold. Yesterday, I (feel)...................terrible, but I am feeling a bit better today 4, I (meet)...................her at the movie theater last night -giúp e vs- cảm ơn