用括号内所给词的适当形式填空 He wants to eat a ____【balance】diet.

用括号内所给词的适当形式填空 He wants to eat a ____【balance】diet.
Drinking milk is good for our_____[healthy].
The man has a serious _____[ill],so he can't go to work.
It'simportant fou us _____[speak]English as much as possible.
My sister______[start] to write her letter an hour ago.