Cho 3 quả cầu kim loại tích điện lần lượt tích điện là +3C, -7C và –4C. Khi cho chúng được tiếp xúc với nhau thì điện tích của hệ là
A.– 8 C.
B.+ 14 C.
C.+ 3 C.
D.– 11 C.

Có thể làm thước nhựa nhiễm điện bằng cách
A.Áp sát thước nhựa vào một đầu của thanh nam châm
B.Có xát thước nhựa bằng mảnh vải khô
C.Hơ nóng thước nhựa
D.Áp sát thước nhựa vào một cực của pin

Mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to the following question.
If I ________ the opportunity to put my knowledge into practice, I _________ more practical experience.
 
A.have/ will gain
B.had/would gain
C.had had/ would gain
D.had had/ would have gained

Mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to the following question.
If you _______ to my advice, you _______ in trouble now.
 
A.listened / were not
B.had listened / would not be
C.had listened / would not have been
D.listen / are not

Mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to the following question.
If you __________ more about how to use the Internet for studying before, you _____ a successful lifelong learner now.
A.had learnt, would have been
B.learnt/would be
C.learn, would be
D.had learnt/would be

Mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to the following question.
If I ______ my knowledge with others, I ______ more ideas on how to find a more suitable job now.
A.shared/ would have had
B.had shared/ would have had
C.share/ would have
D.had shared/ would have

Mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to the following question.
If it _______ warm yesterday, we would have gone to the beach.
A.could be
B.had been
C.were
D.was

Mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to the following question.
If I ___________ some experience in solving problems, I ________ promoted to a new position by now.
A.had gained/ will be
B.gained/ would be
C.had gained/ would be
D.had gained/ would have been

Mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to the following question.
If you take the 8 a.m. flight to New York you _______ change planes.
 
A.would not to have to
B.could not have to
C.will not have to
D.had not had to

Mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to the following question.
You are not allowed to use the club's facilities _____ you are a member.
 
A.provided
B.unless
C.supposed
D.if