since
till
during
for
Answer is Right!
Answer is Wrong!
The correct answer is D. for.
The word “for” is used to indicate a period of time. In this case, the police have been looking for the person for four weeks.
The word “since” is used to indicate a point in time from which something has been happening. In this case, the police have been looking for the person since he disappeared.
The word “till” is used to indicate a point in time up to which something happens. In this case, the police will continue to look for the person until they find him.
The word “during” is used to indicate a period of time in which something happens. In this case, the police have been looking for the person during the past four weeks.