例：邓小平爷爷上前把树苗扶正。（改成“被”字句）

树苗被邓小平爷爷上前扶正了。

①雷公公把藏了好久的大鼓重重地敲了下来。（改成“被”字句）

②我们把一株紫丁香栽在老师窗前。（改成“被”字句）

③人们把枣子打下来。（改成“被”字句）

④科学家把淋浴室做成一个密封浴桶。(改成“被”字句)

例：江河里的水被太阳蒸干了。（改成“把”字句）

太阳把江河里的水蒸干了。

⑤那条长长的围巾被蜘蛛织完了。（改成“把”字句）

⑥禾苗被太阳嗮枯了。（改成“把”字句）

⑦屁股会被苍耳刺痛的。（改成“把”字句）

    What's On?

    Electric Underground

    7.30p.m. —1.00a.m.        Free at the Cyclops Theatre

    Do you know who's playing in your area? We're bringing you an evening of live rock and pop music from the best local bands. Are you interested in becoming a musician and getting a recording contract (合同)? If so, come early to the talk at 7.30pm by Jules Skye, a successful record producer. He's going to talk about how you can find the right person to produce you music.

    Gee Whizz

    8.30p.m.—10.30p.m.        Comedy at Kaleidoscope

    Come and see Gee Whizz perform. He's the funniest stand-up comedian on the comedy scene. This joyful show will please everyone, from the youngest to the oldest. Gee Whizz really knows how to make you laugh! Our bar is open from 7.00pm for drinks and snacks (快餐).

    Simon's Workshop

    5.00p.m.—7.30p.m.        Wednesdays at Victoria Stage

    This is a good chance for anyone who wants to learn how to do comedy. The workshop looks at every kind of comedy, and practices many different ways of making people laugh. Simon is a comedian and actor who has 10 years' experience of teaching comedy. His workshops are exciting and fun. An evening with Simon will give you the confidence to be funny.

    Charlotte Stone

    8.00p.m.—11.00p.m.        Pizza World

    Fine food with beautiful jazz music; this is a great evening out. Charlotte Stone will perform songs from her new best-selling CD, with James Pickering on the piano. The menu is Italian, with excellent meat and fresh fish, pizzas and pasta (面食). Book early to get a table. Our bar is open all day, and serves cocktails, coffee, beer, and white wine.

下列哪一种措施对于提高农业生态系统的稳定性是非常有益的？（　　）