They love their daughter so much that th
题型：选择题
问题：
They love their daughter so much that they are always ready to do everything they can ________ her happiness.
A．to make sure of
B．make sure of
C．be sure of
D．to be sure of
They love their daughter so much that they are always ready to do everything they can ________ her happiness.
A．to make sure of
B．make sure of
C．be sure of
D．to be sure of