homework:
1.Mr Brown(teach)English here since he (graduate)from university
2.What they(do) at 2p.m yesterday? They(herd) buffaloes
3.While the boys(play) tennis,it (begin)to rain
4.You (meet) him sofar?
Yes, I already(meet) him
5.Paul often (taken) he bus to school but today he(walk)
6.Where you(travel) last summer? We (travel) to Nha Trang
7.When she (come) in,I (practise) the violin
8.What you(buy) two days ago?
I(buy) a dictionary
9.How long she(be) in Vietnam? She(be) here for 2 years
10.What you (do) at this time yesterday? I (talk) to my penpal friend
11.Jame ( not come ) to the party last night because she (be) busy
12.While I(want) for bus, I (See) an accident

`a,`

 `Al_2O_3 + 3H_2SO_4 -> Al_2(SO_4)_3 + 3H_2O `

`n_{Al_2O_3} = (20,4)/(102)=0,2(mol)`

`n_{H_2SO_4}=(17,64)/(98)=0,18(mol)`

Ta có: 

`n_{Al_2O_3} (=(0,2)/1) > n_{H_2SO_4}(=(0.18)/3)`

`=>Al_2O_3` dư, `H_2SO_4` hết

theo pt: 

`n_{Al_2O_3 dư} = 0,2 – (0,18)/3 =0,14(mol)`

`=> m_{Al_2O_3 dư} =0,14.102=14,28(g)`

`b,`

`n_{Al_2(SO_4)_3}=(0,18)/3=0,06(mol)`

`=> m_{Al_2(SO_4)_3}=0,06.342=20,52(g)`

Rewrite sentence
1.jenny is a skillful tennis player
-Jenny plays
2. this is the first time Loan has watched a horror film
->loan has
3. Paul can't fix the washing machine
->The washing machine
4.Hoa was so tired that she didn't go to school
-> Hoa was too
5.Please help me on I won't do it by my self
->if
6.When did you start using this bike?
-> How long 
7.David is too young to see horror films
->David isn't
8.Jenny has just made a lot of cakes
->A lot of cake
9.The weather is terrible so I can't go out
->If
10.We started working in the garden 2 hours ago
->We have 
11.Mary didn't send me gifts on my birthday
->I
12.I haven't seen him since 1990
->The last time

Rewrite sentence
1.jenny is a skillful tennis player
-Jenny plays
2. this is the first time Loan has watched a horror film
->loan has
3. Paul can't fix the washing machine
->The washing machine
4.Hoa was so tired that she didn't go to school
-> Hoa was too
5.Please help me on I won't do it by my self
->if
6.When did you start using this bike?
-> How long 
7.David is too young to see horror films
->David isn't
8.Jenny has just made a lot of cakes
->A lot of cake
9.The weather is terrible so I can't go out
->If
10.We started working in the garden 2 hours ago
->We have 
11.Mary didn't send me gifts on my birthday
->I
12.I haven't seen him since 1990
->The last time
 

correct mistakes
1.we still went swimming nearby a river despite it rained
                  A                         B                       C       

heavily
     D
2. the muong ethnic people in Cuc Thuong live mainly in
                                     A                                 B               C 

farming and bee keeping
                            D
3. Hoa some times plays table tennis   more better than
                                   A                  B               C
her close friend does 
               D
4 My father gets used to work on anigh shift so he
                                        A                                 B
doesn't feel     sad
         C                D
5.When tom visited Alashd, she lived in a igloo in the
       A                                              B              C
winter  months as well as in the spring.
                         D
6. the study of the sculptures of the Cham are truly
                         A                                           B
fascinating, and Some books have been written about them.      
                              C                                      D
7. Our grandmother used to be telling as jairy tales when we were small
                   A                               B                         C               D
8 .Kim Speaks English more fluently in the science class 
                A                       B                 C             D