meaning of "Pouring rain"

[Wsevolod]

English Grammar Error, Intermediate level

ESL/EFL Test #20 "Singular vs. Plural Nouns", question 8

I've been walking for ages in the pouring rain and as a consequence my clothes is wet through.

(a) for
(b) pouring
(c) is

English Grammar Error, Intermediate level

ESL/EFL Test #20 "Singular vs. Plural Nouns", answer 8

I've been walking for ages in the pouring rain and as a consequence my clothes are wet through.

Correct entry: are
The error was: (c) is
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Why is it here used "pouring rain"?

Wsevolod

[Mister Micawber]

.
Pouring rain = hard rain.
.
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Native English teacher at Mister Micawber's