there's nothing but …

there's nothing but do
have no choice but to do

there's nothing but sth.
There is nothing but water.（那里除了水，别无所有。）
have no choice but to do
比较：
I have no choice but to give in.
I have nothing to do but give in.(因为前面“to do”中已经有了“to”了，所以后面的“to”要省略。)
（我别无选择，唯有屈服。）

第一个doing

第二个to do

1 doing
2 to do

There is nothing but do
have no choice but to do

doing; to do