Mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to the following question.
We ... for the bus for 20 minutes now, I think the bus….......
A.have been waiting - has been crashing
B.have waited - has crashed
C.have waited - has been crashing
D.have been waiting - has crashed

Mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to the following question.
The homework my teacher assigned me is endless. I ___________ it all day but still _______yet.
A.have doing/ have not been finishing
B.have done/ have not been finishing
C.have been done/ have not finished
D.have been doing/ have not finished

Mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to the following question.
It’s time Tom had to tidy his garden. It’s getting ___________.
A.more and more messy
B.more messy and messy
C.more messier and messier
D.messier and messier

Mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to the following question.
Since he (leave) ______ here no one (see) ______ him.
A.has left – saw
B.had left – saw
C.left – have seen
D.left – has seen

Mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to the following question.
He spent a year in India and loves spicy food. The _______ the food is, the _______ he likes it.
A.hot – more
B.hot – much
C.hotter – much
D.hotter – more

Mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to the following question.
Their new kitchen looks fantastic. They______it for 5 hours.
A.have redecorated
B.already redecorated
C.have been redecorating
D.didn’t redecorated

Mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to the following question.
Getting a job these years is becoming _______________ and the unemployment rate kept rising each year.
A.competitiver and competitiver
B.more and more competitive
C.more competitiver and competitiver
D.more competitive and competitive

Mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to the following question.
I think the waiter _______ us. We _______ here for 30 minutes!
A.has been forgetting - have waited
B.has forgotten - have waited
C.has forgotten - have been waiting
D.has been forgetting - have been waiting

Mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to the following question.
There is only a little cake left because your dad (eat) _______ it in the past 3 days.
A.ate
B.has eaten
C.has ate
D.has been eating

Cho hình chóp $S.ABCD$ có đáy $ABCD$ là hình vuông tâm $O$ cạnh bằng $a,SA$ vuông góc với đáy$\left( ABCD \right)$, $SA=a$. khoảng cách giữa hai đường thẳng $SC$ và $BD$ bằng bao nhiêu?
A.$\dfrac{a}{\sqrt{7}}$.   
B.$\dfrac{a}{\sqrt{6}}$.      
C.$\dfrac{a}{\sqrt{5}}$.
D.$\dfrac{a}{2}$.