（    ）20．It's hard to keep the house _________with three kids.

      A．cleaned               B．to clean               C．clean                   D．have cleaned

A

    Do you know kind words and light music（轻音乐） have something to do with plants?

    Many people talk to their plants．Many people play music to their plants．And many people try very hard to protect（保护）their plants from loud noises，strong lights，and unpleasant（讨厌的）smells（气味）．

    That’s not all．Some people are very careful（小心的）about what they say or do in front of plants．They won’t talk about unpleasant things．They won’t beat（拍打）a fly（苍蝇）near their plants．

    Why? Those people are afraid that they may hurt their plants’ feelings．

    Can you hurt a plant’s feelings? Do plants have feelings? Professor Backster thinks so．Many pupils think so．Even a few scientists think that plants have feelings．

    But most scientists（科学家）don’t agree（同意）．They don’t think that plants can be happy，worried，angry，loving or frightened（害怕）．They don’t believe that a plant’s feeling can be hurt．

    Who is right?

    Then along came the experiments（实验）of professor Backster．From his experiments，Backster decided that plants have feelings．He said that，like people，plants need love and kindness（亲切）．They Call feel worded and happy．

（    ）19．Don't worry! I'm sure I can run ___________ to catch .up with them.

A．fast enough         B．enough fast         C．enough slowly       D．slowly enough

（    ）18．Which sigh tells you the way into a building?

      A．EXIT                 B．PUSH                 C．PULL                    D．ENTRANCE

（    ）17．Sunglasses can protect our eyes _________the sunlight.

      A．of                   B．from                C．for                  D．to