Terrible grammar and error-riddled speech is frequently a problem for young adults.

Poor English makes you sound unprofessional and can lead to laughs at your expense! If you need to touch up on your English, or just want a few giggles, read on!

~ Please return my book back.
~ Could you repeat that last line again?

In both cases, the final word is redundant. When you return a book, you give it back to the owner. When you repeat a line, you're saying it again. They should read:

~ Please return my book.
~ Could you repeat that last line?

~ I, my sister and Deepa went to the mall

'I' and 'me' are always placed at the end of a list of names/ pronouns. The correct usage is:

~ My sister, Deepa and I went to the mall.

~ The fish aquarium is very large.
~ The dance ballet was lovely.

In both cases, the descriptive word is unnecessary. An aquarium houses fish and a ballet is always a dance! The correct usage is simply:

~ The aquarium is very large.
~ The ballet was lovely.

~ I could not able to do it, sir.

In this case, either able should be removed or could should be replaced with was. Here are the two correct possibilities:

~ I could not do it, sir.
~ I was not able to do it, sir.