____he'll return from New Youk depends a great deal on his health.

____he'll return from New Youk depends a great deal on his health.
____he'll return from New Youk depends a great deal on his health.

____he'll return from New Youk depends a great deal on his health.
if 也可以的呀
这种情况下是两者通用的
但是后面有or not 的情况下只能用whether