Know your English !! Part.I

Expletive: Any exclamation or oath, especially one considered to be blasphemous or obscene, whether currently or formerly, such as Damn! Or Heavens above! Nowadays, any obscene word can be loosely referred to as an expletive.

Feet of Clay: Phrase used of a highly regarded person revealed to have a character weakness or flaw: it probably comes from a passage in the Book of Daniel. King Nebuchadnezzar had dreams of a huge statue with gold head, silver arms, and so on, down to feet or iron and clay. Daniel interpreted the dream to mean that a future kingdom would be divided, and would eventually crumble like the clay that supported the statue.

Gilding the lily: Trying to improve something that is already beautiful or perfect: dyeing her naturally
blonde hair would just be gilding the lily. The phrase is often taken to be a quotation from Shakespeare, but the words he actually used in King John were: ‘To gild refined gold, to paint the lily… is wasteful and ridiculous excess’.

In the doldrums: Gloomy, down in the dumps, feeling depressed and lazy. It can also be used of economic condition.
The phrase originated as a reference to equatorial seas, where ships were often becalmed.

Grist to the mill: Something that can be turned to one’s advantage or something that should prove useful even thought it may not appear particularly promising at first. The image is of an old grain mill such as a watermill, which treats anything presented to it as grist or grain, and grinds it regardless.