somebody,someone, something, somewhere一般情况下用于肯定句 anybody,anyone, anything, anywhere一般情况下用于否定句和疑问句 none, nobody, nothing, nowhere 表否定含义 everybody, everyone, everything, everywhere 可用于各种句式 .....·...........·.....

1c Read 1a and complete trees' functions. Tree's functions A.Trees can stop the wind from blowing the earth away.B. A lot of water can be saved by forests. C.They can also stop the water from washing the earth away.