________ you stepped into the lab with your shoes on? You’re supposed to take them off before you enter it. I told you so!

He is badly down these days. This sentence probably means _____.

Isshoppinghereveryexpensive?—Yes,thepricerun _______fiftydollars.[ ]

It is reported that China has created the first man-made sun in the world recently, ______ ?

This is the first time I ______, so I feel very curious about everything here.