1. Word families.

Which words can you use to complete the four sentences below?

A. The asteroid impact will ___________ a nuclear winter effect.
B. Thousands of asteroids ____________ our planet every year.
C. Scientists are trying to__________ the probability of XF11 hitting the Earth.
D. NASA were quick to __________ the IAU's findings.

2. Word building.

Write the noun form of the verb in bold in the gap.

For example:
NASA said that the IAU's announcement highlighted the need to discuss how the discovery of near-Earth objects is announced.

3. Word building.

Write the noun form of these verbs.

4. Word building.

Complete the sentences by writing the noun or verb form of the words from exercise 3. Be careful to use the correct form of the verbs.

5. One word.

Which one word can be used to complete all the sentences?

NASA's research was carried ___ after the IAU's announcement.
An asteroid could hit Earth, wiping ___ our civilisation as we know it.
A life-threatening collision could not be ruled ___ .
The nuclear winter effect after impact would blot ___ the sun.

6. Word focus: phrasal verbs with out.

The adverb out has two main meanings when used as part of a phrasal verb.

Something appears or is
brought to a conclusion.

The sun came out from behind a cloud.

Other verbs in this group:
carry out

Something disappears.

Scott
Rob
Nicky
Gavin
Fiona

Two names on the list were crossed out.

Other verbs in this group:
wipe out, rule out, blot out

Complete the sentences with the verbs below.

For more information about phrasal verbs see the Grammar Reference.

7. Phrasal verbs with out.

Now put the verbs from exercise 6 into one of the boxes below to show what the meaning of out is.