Dãy các chất nào sau đây đều là hiđrocacbon?
A.C2H6, C4H10, C2H4.
B.CH4, C2H2, C3H7Cl.
C.C2H4, CH4, C2H5Cl.
D.C2H6O, C3H8, C2H2.

She _______ on her computer for more than two hours when she decided to stop for a rest.
A.has worked
B.has been working
C.was working
D.had been working

You can trust me not _______ anyone.
A.tell
B.to telling
C.to tell
D.telling

Before she went to bed, she ______ her homework already.
A.finished
B.is finishing
C.had finished
D.was finishing

Hiện tượng khống chế sinh học trong quần xã dẫn đến hệ quả nào?
A.Đảm bảo khả năng tồn tại của quần xã.
B.Đảm bảo cân bằng hệ sinh thái.
C.Làm mất cân bằng sinh thái.
D.Làm cho quần xã không phát triển được.

She is an honest person. She is also a very friendly one.
A.She is an honest but friendly person.
B.She is not only an honest but also a very friendly person.
C.Though she is an honest person, she is friendly.
D.Being honest is necessary to become friendly.

Most artists find it _______ impossible to make a living from art alone.
A.mostly
B.much
C.almost
D.a little

His academic record at high school was poor. He failed to apply to that famous university.
A.His academic record at high school was poor because he didn’t apply to that famous university.
B.His academic record at high school was poor as a result of his failure to apply to that famous university.
C.Failing to apply to that famous university, his academic record at high school was poor.
D.His academic record at high school was poor; as a result, he failed to apply to that famous university.

Cho 18 gam glucozơ tráng bạc hoàn toàn, khối lượng bạc thu được sau phản ứng là
A.68,1 gam.
B.21,6 gam.
C.10,8 gam.
D.43,2 gam.

Đốt cháy hoàn toàn một ankađien X ở thể khí thu được H2O và CO2 có tổng khối lượng là 23 gam. Nếu cho sản phẩm cháy đi qua dung dịch Ca(OH)2 dư, được 40 gam kết tủa. Công thức phân tử của X là
A.C2H2.
B.C3H4.
C.C4H6.
D.C5H8.