单选题

There are five questions below，

Exactly six lectures will be given one at a time at a one- day conference.Two of the lectures—S and T—will be given by residentspeakers, the other four—W, X, Y, and Z—will be given by visiting speakers. At least two but no more than four of the lectures will be given before lunch; the remaining lectures will be given after lunch. The following conditions must be observed:

S will be the fourth lecture. Exactly one of the lectures by a resident will be given before lunch.

Y will be given at some time before T is given. If W is given before lunch, Y will be given after lunch.

单选题

Which of the following can be the order of lectures and lunch at the conference?

A、 W, X, Lunch, Y, S, T, Z
B、 X, Y, T, Lunch, S, Z, W
C、 Y, T, Lunch, S, W, X, Z
D、 Z, T, W, S, Lunch, Y, X
E、 Z, W, Y, S, Lunch, X, T

【正确答案】 B

【答案解析】

单选题

If exactly two lectures are given before lunch, they must be

A、 X and T
B、 Y and T
C、 Z and T
D、 Z and W
E、 Z and Y

【正确答案】 B

【答案解析】

单选题

If exactly three lectures, including Y and Z, are given before lunch, which of the following can be true?

A、 T is the second lecture.
B、 T is the fifth lecture.
C、 W is the third lecture.
D、 X is the first lecture.
E、 X is the third lecture.

【正确答案】 A

【答案解析】

单选题

If T isthe sixth lecture, which of the following must be true?

A、 X is the first lecture.
B、 X is the second lecture.
C、 Exactly two lectures are given before lunch.
D、 Exactly three lectures are given before lunch.
E、 Exactly four lectures are given before lunch.

【正确答案】 E

【答案解析】

单选题

If S and Z are both given after lunch, which of the following must be true?

A、 X is given before lunch.
B、 X is given after lunch.
C、 Y is given before lunch
D、 T is the third lecture.
E、 Z is the fifth lecture.

【正确答案】 C

【答案解析】

单选题

Which of the following lectures CANNOT be given immediately before lunch?

A、 S
B、 T
C、 X
D、 Y
E、 Z

【正确答案】 D

【答案解析】