An unusual topic surfaced this week when looking at an event in history.
Did you know that an international treaty, originally signed by 30 nations but now by 77, that bans weather warfare, was signed this week in 1978.
"Weather warfare? What's that?", you say!
It was first used by the US Army in the Vietnam War at great cost, and with unclear results.
Firing chemical bullets into the sky to cause the formation of clouds, known as cloud seeding, was a technique used to try and induce the rainy season earlier than expected. The hope was that the wet and muddy conditions on the ground would make it difficult for opposing forces to make gains, putting the US Army at an advantage.
More recently, the Chinese were said to have used similar methods to make the Olympics in 2008 a dry one!
Words and usage: when
It's a question word we all know, which in simple English form means 'at what time?', but it is also used as a conjunction meaning 'at the time'. This conjunction is usually followed by a less important clause.
It can appear at the start of a sentence before the main clause, or after it.
Other forms and uses can be found at Oxford Dictionaries.
Grammar point: 'were said to have used...'
Looking back at a past time from a past time point, we can use this for passive forms when talking about others' actions.
'Be....' can also followed by 'said', 'known', 'reported' and 'believed'.
More explanation can be found at The British Council website.
Practice: Tell us what you would change about the weather, and explain how you think you could achieve it.
Quiz Me! Conversation card: Card A5 below is from General Level 2, pack 1.
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