It is the test system, _____ the teachers, that is to blame for the heavy burden of middle school students nowadays

On weekends, we like TV at home.

When I got on the bus，I ________ I had left my wallet at home.(2011·山东)

It’s clear that ________ little money he earns can hardly support his family.

_________ scientist like her won’t besimply satisfied with _________ little progress that has been made.