__ is really hard __ them to climb Mount Tai.
| A．This, to | B．It, for |
| C．This, for | D．It, to |
----Where is your sister?
-----She _________ my mom with cooking.
| A．is helping | B．helping | C．is help | D．helps |
Which of the following doesn’t belong to the Four Great inventions of Ancient China?
| A．Compass | B．Gunpowder | C．Paper-making | D．Printer |
Our planet is about years old.
| A．35,000 | B．4600 | C．4600 million | D．500 million |
can cause high blood pressure and hearing problems.
| A．Air pollution | B．Water pollution | C．Light pollution | D．Noise pollution |
is one of the greatest scientists, who won the Nobel Prize for physics.
| A．Yuan Longping | B．Bisheng | C．Yang Zhenning | D．Zheng He |