Some people who have received the vaccine might decide that they can take on risks that they might not have before.
Maybe they want to travel or get that hug from a grandchild remember that the vaccine is still not one hundred percent effective.
So it's important to keep up other measures like masking to reduce risk.
请教老师：...they can take on risks that they might not have before. 怎么样理解这里的定语从句that they might not have ?
是否如此： they can take on risks that they might not have before. ？
若是如此的话，为何不是might have not takend on...我什么是might not have taken on...呢？
另外，为何take on risks , 而句尾处reduce risk （却是单数）？
1 是如此： they can take on risks that they might not have before.
taken on省略了。might not have done sth 为推断过去可能没做过某事。（打疫苗前没冒过的风险）
not 的地方是操作词之后。这里操作词为might, 而不是have，have是不带to的不定式，不是操作词。
2 to reduce risk. 这里risk为不可数名词。
