L081_DJQ046_Why are manhole covers round? 【Tambaboon English IELTs study Lab Sydney Australia】 アイエルツ 英語

This is quite difficult question because the exact reason.

1. This is quite a difficult question 
2. because I am not sure the exact reason. 

However I can guess firstly manhole are round to clean easily.

1. However, 
2. I can guess firstly manholes are round 
3. because they are easily cleaned.

I mean if manhole is square shape, the corner section is difficult to clean.

1. I mean, 
2. if a manhole is a square shape, 
3. the corner section would be difficult to clean.

★ English grammar - IF clause
★ English grammar - would

It should be dirty soon.

1. It would become dirty quickly.

★ English grammar - would

However, if it is round shape, just we can wipe the wall simple.

1. However, 
2. if it is a round shape, 
3. we can just clean the edges easily.

I guess manhole has to be round, so manhole cover also round.

1. I guess manholes have to be round, 
2. so manhole covers are also round.

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• This is a brain teaser, the common answers are:

• "Because if it weren't a shape of constant width, it could fall in" 

(If you had a square manhole cover, 
the length of any side is shorter than the length of the diagonal, so it could fall in)

• "Because manholes are round" (this is kind of a joke answer)

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