8, three American scientists invented ____transistor, which is ____ small electronic device to control an electriccurrent.

下列各句中，没有语病的一项是（ ）

Hi, Susan, you look tired.—I for months for the coming celebration of our school’s 90th anniversary

Merry________ B．has worked C．is working D．works

Most middle schoolsprefer to buy _______ desks, so they can change to suit students’ growingheight.