Sleeping in bed ,I could hear the rain --against the windows

要选择C beating
躺在床上,我可以听到雨点打在窗子上的声音.
rain beating the windows
不用dropping 掉落在 后面要用on
dropping on the floor/windows
hitting,打击,一般不说雨点hitting the windows
string这是个名词,细绳