\(2Na + 2H_2O →2NaOH + H_2\)

\(→ n_{Na} = \dfrac{m}{M} = \dfrac{9,2}{23} = 0,4 (mol) \)

\(\Rightarrow m_{NaOH} = 0,4 . 40 = 16 ( g)\)

Bán kính hình tròn là : \(d = 2r →\dfrac{1}{2}×d = \dfrac{1}{2} × 4 = 2 (cm)\)

Diện tích hình tròn : \(A = π .r^2 → A = 3, 14 ×2^2 =12,56 (cm^2).\)

\(/t/ :\) asked, stopped, looked, watched, checked

\(/id/ :\) visited, started, weighted, needed

\(/d/ :\) called, filled, measured

\(1.\)They enjoy traveling to Nha Trang on their vacation. ( HTĐ)
\(∘\) Cấu trúc : S \(+\) enjoy/like/love/prefer \(+\) V_ing ....
\(2.\) You ought not to watch TV too late. ( ought not to \(=\) should not )
\(∘\) Cấu trúc : S \(+\) ought not to V-inf \(+...\)
\(3.\) Nam is going to visit his grandparents tonight.(HTTD)
\(∘\) Cấu trúc : S\(+\)am/is/are \(+ \)V_ing \(+...\)
\(4.\) How much do these sweaters cost?
\(∘\) How much \(+\) to be \(+\) N?\(=\) How much \(+ \)aux V \(+\) S \(+\) cost?
\(5.\) Lan Anh is a hard student. ( student : n \(→\) đi sau adj \(−\) hard : adj )
\(∘\) S \(+\) V \(+\) adv. \(=\) S \(+\) to be  \(+\) adj \(+\) N

He said to her (that) she was wearing her best clothes. ( câu tường thuật \(−\) kể )
\(∘\) Cấu trúc:  S \(+\) said ( to sb )\(+\) ( that ) \(+\) S \(+\) V ( lùi thì )

John told Mary that she was ready to go with them ( trực tiếp  \(→\) gián tiếp )
\(∘\) Cấu trúc : S \(+\) said / told / ...\(+\)... O \(+\) that \(+\) S \(+\) V ( lùi thì )

\(2.\) Everyone is affected by crime in different ways.

\(-\) Câu bị động thì hiện tại đơn: S \(+ \) am/ is/ are \(+\)(not) \(+\)V (P_II) \(+\) (by O).

\(3. \)You'd like to have a look at my new car, don't you?

\(-\)  Phần mệnh đề ở dạng khẳng định thì phần láy đuôi ở dạng phủ định và ngược lại.

\(+\) Statement: S \(+\) V (s/es).

\(+\) Tag: don't/ doesn't \(+\) S?

\(-\) S \(+\) want \(+\) to V \(=\) S \(+\) would like \(+\)to V: Ai đó muốn làm việc gì…

\(C+O_2\xrightarrow[]{t^o}CO_2 \)

\(\rightarrow n_C=\dfrac{2,4}{12}=0,2 (mol) \)

\(Theo PT :\) \(n_C = n_{O_2}=0,2(mol)\)

\(\Rightarrow V_{CO_2,đktc}=0,2\times22,4=4,48(l)\)