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Please help me correct if I got any mistakes, thanks!

Last school holidays, Peter and his friends decided to go outings. They cycled (their bicycles) and passed by an orchard. They saw many mangosteens on the trees. They were ripe and looked tempting. / looked mouth-watering.

They parked their bicycles under a tree. Then, they climbled the tree one by one and plucked mangosteens. They were enjoying themselves on the tree. Suddenly, they noticed the orchard's owner / owner appeared and waiting under the tree.

They were astonished and dreadful at that time / during that time / at the moment. They immediately climbed down the tree and apologised to the owner. Luckily, the owner was kind. He did not scold them but advised them to get permission (from him) first (to pluck the fruit). They felt ashamed / embarrassed for their wrongdoing.
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I suggest fixing the following:

decided to go outings.

Suddenly, they noticed the orchard's owner / owner appeared and waiting under the tree.

They were astonished and dreadful
Comments  
Thanks, how about the rest of the sentences?