there are ten mistakes in the following passage. Find them and write your corrections

It is very important for use water carefully. Here are some way you can use much water. First, you should be surely you turn of the faucets tightly. They should not drip in the bathroom or kitchen sink. Second, you should not keep the water on in a long time. You should turn it off while you are doing something else. It should be off while you are shaving or washing your teeth. It should also be off while you are washing the dishes. Final, in the summer you should watering the garden in the evening. That way you will not lose a lot water. During the day the sun dries up the earth too fastly.

Fill in the blank with one preposition

1, Nobody helped him to do this work. He managed to do it............... his own.

2. He has a new solution ................. the problem.

3. Do you know any sóng ................. the Beatles?

4. his attitude .......... His job is very negative.

5. I'm just going out to do some shopping. I'll be back ......... half an hour

Cho mạch điện như hình vẽ:

R₁ =R₂=5Ω

R₃=R₄=5Ω

a, K mở tích U₁.

b, K đóng tính I_K