@oristarA,
oristarA wrote:
"The mutation causes the virus resistant to the drug." ...
...I know it was suspicious and awkward that is why I posted the thread. But I failed to know why. Could you explain it?
The sentence is in the form: The [noun] causes the [noun] [adjective]. This is an incomplete sentence.
Can you see why these are wrong?
Beer causes my mother aggressive.
Prolonged hard work causes me tired.
The verb 'cause' requires either a noun or if the thing caused is denoted by an adjective, then a verb like 'to be', 'to become', to [do something].
The sentence asked about should be in the form:
The [noun] causes the [noun] to become (or be) [adjective]
The mutation causes the virus to become resistant to the drug.
Beer causes my mother to become aggressive.
Prolonged hard work causes me to become tired.
An alternative might be to use "makes":
The mutation makes the virus resistant to the drug.
Beer makes my mother aggressive.
Prolonged hard work makes me tired.