X là 1 amin đơn chức, Y chứa các nguyên tố C, H, Cl và Z chứa các nguyên tố C,  H 2 O . Chất X, Y có cùng khối lượng phân tử. Trộn X, Y, Z theo tỉ lệ số mol 1:1:1 thì được hỗn hợp A, và theo tỉ lệ 1:1:2 ta được hỗn hợp B. Đốt cháy hết 2,28 g A thu đc 3,96 gam  CO 2 ; 1,71 gam  H 2 O và hỗn hợp khí D. Biết khi đốt cháy X tạo  N 2 còn khi đốt cháy Y tạo  Cl 2 , cho D qua ống đựng Ag nung nóng để hấp thụ hết  Cl 2  thấy khối lượng tăng thêm 0,71 gam. Để trung hòa 2,28 gam hỗn hợp A cần 100 ml dung dịch HC1 1M, còn để trung hòa hết 2,28 gam B cần 79,72 ml dung dịch HC1 0,1 M. CTPT của X, Y, Z lẩn lượt là:

A.  C 6 H 13 N ,   C 2 H 4 Cl 2 ,   C 3 H 6 O

B.  C 5 H 11 N ,   CH 2 Cl 2 ,   C 3 H 6 O

C.  C 5 H 11 N ,   CH 3 Cl ,   C 4 H 6 O

D.  C 6 H 13 N ,   C 2 H 4 Cl 2 ,   C 4 H 6 O

An nói với Bình: “Mình đi mà hóa ra đứng; cậu đứng mà hóa ra đi!”. Trong câu nói này thì vật làm mốc là ai?

A. An.

B. Bình.

C. Cả An lẫn Bình.

D. Không phải An cũng không phải Bình.

Mark the letter A, B, C, D on your answer sheet to indicate the word that is CLOSEST in meaning to the underlined part

The nurse told her that she would have to wait for a few days for the outcome of the medical check-up

A. putting 

B. payment 

C. result 

D. coming

Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions.

Lead poisoning in children is a major health concern. Both low and high doses of paint can have serious effects. Children exposed to high doses of lead often suffer permanent nerve damage, mental retardation, blindness, and even death. Low doses of lead can lead to mild mental retardation, short attention spans, distractibility, poor academic performance, and behavioral problems.

This is not a new concern. As early as 1904, lead poisoning in children was linked to lead- based paint. Microscopic lead particles from paint are absorbed into the bloodstream when children ingest flakes of chipped paint, plaster, or paint dust from sanding. Lead can also enter the body through household dust, nailbiting, thumb sucking, or chewing on toys and other objects painted with lead-based paint. Although American paint companies today must comply with strict regulations regarding the amount of lead used in their paint, this source of lead poisoning is still the most common and most dangerous. Children living in older, dilapidated houses are particularly at risk.

According to the passage, what is the most common source of lead poisoning in children?

A. household dust 

B. lead-based paint 

C. painted toys 

D. dilapidated houses