题目内容：

He has r_ thet the poison will kill finish and plants inthe river.
The doctor told the patient that his health could be a_ by a lot of elements.(因素)
My cousin should study even _(hard) at all his subjects _(catch) up with his classmates.
He decided _(not drop)_(learn)physics well.Because he finds it useful.

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He has （realized） thet the poison will kill finish and plants inthe river.
The doctor told the patient that his health could be (affected) by a lot of elements.(因素)
My cousin should study even (harder) at all his subjects (to catch) up with his classmates.
He decided (not to drop) (learning) physics well.Because he finds it useful.