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.
Antonym analogy: Excite↔Calm. Similarly Stimulate↔Cool down.
Antonym analogy: Delay↔Expedite. Similarly Detain↔Dispatch.
Anarchy = absence of Government. Penury = absence of Wealth. Same analogy.
Vaccine is used to prevent disease. Antidote is used to counteract poison.
'Although' shows contrast between glass appearing solid but having liquid molecular structure.
The criminals escaped before the search — earlier past action takes past perfect 'had escaped'.
'Live beyond the margins' = live outside the conventional boundaries of mainstream society.