a、b取何值时，线性方程组 有唯一解、无解、有无穷多解？并在有无穷多解时，求出方程组的通解.

听力原文：W: I ought to call Joan and tell her about the reception of this evening.

M: Why bother？ You'll see her at lunch.

What does the man mean？

A．The woman can tell Joan when she sees her at noon.

B．The woman should tell Joan's brother about the reception.

C．The woman must call on Joan after the reception.

D．The woman may see Joan's brother at lunch.

A．Withpleasure

B．Nevermind

C．You’rewelcome

D．Justaminute

听力原文：W: I ought to call Joan and tell her about the meeting this afternoon.

M: Why bother？ You'll see her at lunch.

Q: What does the man suggest the woman do？

(16)

A．Ask Joan to come to the meeting before lunch.

B．Tell Joan at lunch about the meeting.

C．Call Joan to meet her for lunch.

D．Meet Joan in the hall after lunch.

-Could you tell Lucy about the news when you see her？ -Sure,I will()I see her.

A. certainly

B.fortunately

C. probably

D.immediately

nference held in the Central Hall？ I ought to call Susan and tell her the exciting news now.

M: Why bother？ You'll see her at supper.

Q: What does the man suggest the woman to do？

(16)

A．To ask Susan to give a speech before supper.

B．To meet Susan in the hall after supper.

C．To call Susan immediately and tell her the news.

D．To tell Susan at supper about the news.

She asked you when＿＿＿again？

Tell her that I，ll let her know when he＿＿＿．

—Could you tell Lucy about the meeting when you see her？ —Sure, I will______ I see her.

A．certainly

B．fortunately

C．probably

D．immediately

______ you call me to say you're not coming, I'll see you at the theatre.

A．Though

B．Whether

C．Until

D．Unless