Máy cơ đơn giản nào sau đây không cho lợi về cả lực hay đường đi: A. ròng rọc cố định B. ròng rọc động C. đòn bẩy D. mặt phẳng nghiêng.

Các câu hỏi liên quan

1 - Mrs. Allen wrote that novel in 1998. - .................................................................................................. 2. Nam borrowed the reference book from the shelf yesterday. - .................................................................................................. 3. The boy ate two loaves of bread last Sunday. - .................................................................................................. 4. He left the letter on the desk some minutes ago. - .................................................................................................. 5- My mother bought a new bike for me last month. - .................................................................................................. 6- Our form teacher returned our written test to us last lesson. - .................................................................................................. 7- The Chinese invented paper in the century A.D. - .................................................................................................. 8- Vietnamese planted trees in their neighborhood a year ago. - .................................................................................................... 9- The children played games yesterday. - .................................................................................................... 10- My sister did the housework yesterday. - ....................................................................................................