Fill in the Blanks

(its): ‘crowd’ is a collective noun and is spoken of as one whole. 

(played). Past indefinite tense is used. 

You excel at an activity. ('in' is used with a subject.)

(Both): Conjunction ''and'' is preceded by ''both'' and ''both'' is used for two people or things.

(a flightless bird). Noun phrase in apposition to the subject. All the other options except (3) make use of connecting words which convert the phrase to a clause.

(Because of). Here the reason is the most important part of the sentence, so we make use of 'because'.

(the colourless gas nitrogen is also present). Option (1) provides the correct word order. Options (2) ,(3) and (4) make use of unnecessary words, which make the sentence incomplete and meaningless. 

(a branch of science concerned with). Correct word order. All the other options make use of words which makes the sentence incomplete. 

(the praise of even). Option (4) provides the correct word order. Options (1), (2) and (3) make use of unnecessary words, which make the sentence incomplete and meaningless. 

(Tornadoes almost never occur). Correct word order

(the colourful hummingbird). Options (1), (2) and (3) make use of unnecessary words, which make the sentence incomplete and meaningless.

(It was Thomas Nast who). Correct subject

five times as hard as ordinary glass

(Although). Although is the only conjunction of concession given.

(from). Correct preposition because you always take something from somewhere.