3．(　　 )设{a_n}是等差数列，公差为d,S_n是其前n项和，且S₅<S₆, S₆=S₇>S₈．下列结论错误的是

A．d<0　　　　　　　　　　　　　　　 B．a₇=0 C．S₉>S₅ D．S₆和S₇为S_n最大值

2．(　　 )已知在等差数列{a_n}中，a₁＜0，S₂₅＝S₄₅，若S_n最小，则n为

A．25　　　　　　　　　　　　　　　　 B．35　　　　　　　　　　　　　　　　 C．36　　　　　　　　　　　　　　　　 D．45　

1．(　　 )已知等差数列{a_n}中，a₁+a₄+a₇=39,a₂+a₅+a₈=33,则a₃+a₆+a₉等于

A．30　　　　　　　　　　　　　　　　 B．27　　　　　　　　　　　　　　　　 C．24　　　　　　　　　　　　　　　　 D．21　

2.　　　 Preview discovering useful structures.

1.　　　 Review the words and expressions for this Unit.

2. If time permits, continue Exercises 2-4.

Step V. Homework

1. First deal with Ex.1 on page 63.

“What happened when the General went to war?” Students can work in pairs to have a discussion, and then ask some students to give their answers.

　A: The General went away to war.　 Meanwhile his advisers marked his progress on a map so as to be sure of knowing where he was.

B: Meanwhile the gardener planted new flowers in the flowerbeds so as to be able to make a beautiful garden for the General’s return.

　Meanwhile the cook learned to make some new dishes so as to be able to prepare a special banquet when the General returned.

Meanwhile his wife made him some new clothes so as to be able to dress him smartly for the banquet on his return.

Meanwhile his children practiced some new songs and dances so as to be able to perform for the General when he returned.

2.　　　 Ex2 on page 28. Ask the Ss to finish Exercise 2 and then check the answer and make some explanation if needed.

StepⅣ Using words and expressions (P63)

StepⅠ Greetings

StepⅡ Revision

T: Yesterday we talked about the qualities needed to be a good reporter, how to get an accurate story and how to protect a story from accusation. Now I’d like you to tell me what qualities a reporter should have. (Ask a Ss to share their knowledge with others)

StepⅢ Discovering useful words and expressions

1.　　　 Ex1 on page 28. Give Ss directions that they should find the idiomatic expressions used in the text to match with the expressions given in the Activity. Then check and make some necessary explanation.

　A computer, a blackboard, a tape-recorded