Câu hỏi: The world is becoming more industrialized and the number of animal species that have become extinct have increased.

A. industrialized

B. species

C. extinct 

D. have

Câu 1: A smile can be observed, described, and reliably identify, it can also be elicited and manipulated under experimental conditions.

A. identify

B. experimental

C. can also

D. A smile

Câu 2: Having finished his tem paper before the deadline, it was delivered to professor before the class.

A. having finished

B. before

C. it was delivered

D. before

Câu 3: It is recommended that people to take regular exercise.

A. recommended

B. people

C. to take

D. exercise

Câu 4: My elder sisters, both of them were doctors, said they were too busy to pick me up.

A. elder

B. both of them

C. too busy 

D. to pick

Câu 5: The number of students attending universities to study economics have increased steadily in the last few years.

A. of students

B. attending

C. economics

D. have

Câu 6: More than ten students have failed the exam, that surprised the class teacher.

A. more than

B. have failed

C. that

D. the