Antonym analogy: Eager↔Indifferent. Similarly Enthusiastic↔Halfhearted.
Synonym analogy: Lengthen≈Prolong. Similarly Stretch≈Extend.
Synonym analogy: Delay≈Retard. Similarly Slow down≈Hold up.
Antonym analogy: Submissive↔Disobedient. Similarly Observe↔Defy.
'Fantasize about' is the correct collocation.
Passive perfect infinitive: 'to have been + past participle'. 'to have been erected'.
'Between' for two people/things. 'Among' for three or more.
Simultaneous past action → past continuous 'was discussing'.
'Concrete' here means definite/real. 'Concrete proof' = clear evidence.
'Literally billions' emphasizes the number is not an exaggeration.
Gypsies have no fixed home and wander from place to place — always on the move.
Tents are portable and easy to pitch — suitable for a nomadic lifestyle.
'Take someone for' = mistakenly believe someone to be something.
The passage states the attitude towards gypsies has gradually changed.
'Blow away' = to be moved or carried off by wind.
'Deny' = state something is not true. Nobody can deny his cleverness.
'Employees' is plural → 'have'. Present perfect 'have worked' for past action with present result.
'Celebrate' the arrival of spring; 'organized' a function — the best collocations.