We can't afford to let the situation get worse. We have to take （） to put it right.

单项选择题（）, the researchers cannot concentrate on that very precise experiment.

A．With you standing there
B．On your standing there
C．You are standing there
D．You stand there

单项选择题（） have come up with the solutions to the problem.

A．The boy student
B．The boys student
C．The boy students
D．The boys sutdents