The best way to make sure that your meaning is clear is to keep your sentences short. In short sentences, phrasing is much less likely to be muddled.

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The second example has one idea per sentence. It also keeps the sub-clauses (the smaller clauses, usually enclosed by commas, that add information) next to their subject. This makes the sentences easy to understand.

N.B.

In addition, take care where you put your commas.

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In the first example, the amazement is directed at the chemist.
In the second example, the amazement is directed at the experiment.

To make sure what you've written is clear, and also exactly what you mean, write down what you're trying to say in the simplest possible way. Every time your marker has to write a ? or ‘explain’ in the margin, your work loses value.