G8-U12-L2

In 1957 the Soviet Union _________ the first satellite to orbit the Earth.

• launched

• put up

• erupted

• overcome

They wanted to know when did astronauts orbited the moon and later walked on its surface.

A. wanted                    B. did                           C. orbited                    D. walked

• wanted

• did

• orbited

• walked

. I asked the scientist, “What will happen to the planets when the Sun became a red giant?”

A. will happened         B. when                       C. became                   D. giant

• A

• B

• C

• D

If _______ existed and were living out there, what types of signals would they send us?

• scientists

• astronauts

• aliens

• explorers

Researchers made the amazing findings of _______ of water on Mars.

• footprints

• trips

• paths

• traces

Sarah asked Abigail if scientists could discovered more planets outside the Solar System.

A. asked                       B. if                              C. discovered                          D. outside

• A

• B

• C

• D

. Scientists said that they estimated the age of the universe by using the movement of stars to measure their expanding speed.

A. said                         B. estimated                C. using                       D. their

• A

• B

• C

• D

She asked, “How much _______ about our Solar System?”

• do you know

• you know

• you knew

• you will know

We can only see _______ in the sky at night because during the day the sunlight is so bright.

• the Earth

• stars

• aliens

• UFO

I think the availability of liquid water is the most important factor that makes a planet _______.

• habitable

• unsuitable  

• dead  

• impossible