WHEELS AND FITNESS
The invention of the wheel didn't only improve transport, but also produced many sporting activities. The two wheels on a 1. ...... can take you much faster and further than your two feet. The inventor of 2... decided to put a line of wheels on his shoes. Some people say the 3.... was invented by 4..... who wanted the same experience on land as on the sea, so they put wheels on small boards. Although wheels can help us move more easily, these forms of 5... still require a lot of energy. 6........ up and down tracks in the countryside certainly keeps you fit, and skateboarding will leave you out of 7....... as much as jogging. I tried rollerblading for the first time the other day, and after an hour, I was 8 .....

b)Thực hiện phép tính:  35 – {12 – [-14 +(-2)]}

2) Tính hợp lý:

a. -29x165 + 29x65
b. (215 - [5x(5x16 - 25x2) -60]}:53

Hòa tan muối ăn vào nước ta thu được nước muối. Nước muối được gọi là

A. dung môi.

B. huyền phù.

C. dung dịch.

D. chất tan.

Hình đĩa là hình dạng đặc trưng của loại tế bào nào ở người?

A. Tế bào cơ.

B. Tế bào trứng.

C. Tế bào thần kinh.

D. Tế bào hồng cầu.