Tính  10 21 : 2 3

1. That tower was very high. We couldn't limb it up

That is such a high tower that we couldn't climb it up.

2. The tale story is very exciting . We want to hear it again

It is such an very exciting tale story that we want to hear it again.

3. I don't think Mary is old enough to get married

I think Mary is not old enough to get married

Chuyển thành câu bị động
1. I want you to do this work now. \(\Rightarrow\) I want this work to be done by you now.
2. Have they ever shown that film on TV? \(\Rightarrow\) Has that film ever been shown on TV.

\(\dfrac{4}{\sqrt{3}+1}-\dfrac{5}{\sqrt{3}-1}+\dfrac{6}{\sqrt{3}-3}\) \(=\dfrac{4\left(\sqrt{3}-1\right)}{\left(\sqrt{3}+1\right)\left(\sqrt{3}-1\right)}-\dfrac{5\left(\sqrt{3}+2\right)}{\left(\sqrt{3}-2\right)\left(\sqrt{3}+2\right)}+\dfrac{6\left(\sqrt{3}+3\right)}{\left(\sqrt{3}+3\right)\left(\sqrt{3}-3\right)}\)

\(=\dfrac{4\left(\sqrt{3}-1\right)}{2}-\dfrac{5\left(\sqrt{3}+2\right)}{-1}+\dfrac{6\left(\sqrt{3}+3\right)}{-6}\)

\(=2\left(\sqrt{3}-1\right)+5\left(\sqrt{3}+2\right)-\left(\sqrt{3}-3\right)\)

\(=2\sqrt{3}-2+5\sqrt{3}+10-\sqrt{3}-3\)

\(=6\sqrt{3}+5\)

10 nha bn

\(Từ\dfrac{x}{9}=\dfrac{1}{x}\Leftrightarrow x.x=1.9\)

\(\Leftrightarrow x^2=9\)

\(\Leftrightarrow x=3\)

Chuyển sang câu bị động:

1.Somebody might steal your car if you had left the keys in it.

\(\Rightarrow\) Your car might be stolen if you had left the keys in it.

2.A short circuit could cause the fire.

\(\Rightarrow\) The fire could be caused by a short circuit.

3.They should announce that news as soon as possible.

\(\Rightarrow\) That news should be announced as soon as possible.

Chuyển từ câu chủ động -> bị động

1.Who helped her?

-->By whom she was helped ?

2.Who bake this cake?

-->By whom this cake is baked?

3.Who has written this sentence on the wall?

-->By whom this sentence has been written on the wall ?