a lot of = a mountain of???仲有冇

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a lot of 可用於countable/ uncountable nouns；many只可用於countable nouns
a great deal of 可和 a lot of 相替用, 但只可用於uncountable nouns.
plenty of 可和 a lot of相替用, 可用於countable及uncountable nouns.
未聽過a mountain of.

plentiful = abundent =enough

If you want to tell other there are many mountain you can also say
there are numerous of mountain.

*Numerous of =many of something*