第一种表达：I struggle to do geometry.
第二种表达：I struggle doing geometry.
这两个句子都是正确的。但是接下来是一个有惯用语错误的句子：
Bob insists at being annoying.
看出哪里出问题了吗？正确的表达应该是：Bob insists on being annoying.
再看一个例子：
Julie tends being worrisome.
正确的表达应该是：Julie tends to be worrisome.
