Cho cơ hệ như hình vẽ.
$ \alpha ={{30}^ 0 };{ m _ 1 }=1kg;{ m _ 2 }=2kg. $ Tính công do trọng lực của hệ thống sinh ra khi $ { m _ 1 } $ đi lên không ma sát trên mặt phẳng nghiêng được quãng đường 1m.
A.10J
B.15J
C.20J
D.5J

Mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to the following question.
I saw a line of people ………. outside the store. It must be having discounts.
A.queuing
B.huddling
C.crowding
D.protesting

Mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to the following question.
The …………. are always in need.
A.olders
B.old
C.elders
D.elder

Mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to the following question.
Women who visit the store will be given a ………. on holidays.
A.discount
B.putoff
C.donation
D.downsize

Mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to the following question.
My ………………… to Harvard made the family proud.
A.tuition
B.grant
C.scholarship
D.fee

Mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to the following question.
……… workers used to have to work 12 hours a day and cannot feed their babies.
A.Ladies
B.Unmale
C.Woman
D.Female

Trong các phát biểu về công của lực sau đây, phát biểu nào không đúng?
A.Công luôn luôn dương.
B.Công được tính bằng biểu thức $ A=F.s.c\text{os}\alpha $.
C.Công là đại lượng vô hướng.
D.Công có giá trị đại số.

Mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to the following question.
My family makes sure I ………. blood because my genes can cure cancer.
A.giving
B.donate
C.celebrate
D.charity

Mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to the following question.
His ………. made her fall in love with him.
A.generosity
B.will
C.hope
D.consciousness

Mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to the following question.
………. can identify the patient’s cause of pain and operate on them skillfully.
A.carers
B.nurses
C.surgeons
D.housewives