[单项选择]Blocks of "high-rise" flats have been built in large numbers in London and in many other big cities. Just after the Second World War these big, twenty-to-thirty storey buildings, hundreds of feet in height, were thought to be the ideal solution to the housing problem. For on the one hand, there was severe housing shortage, but on the other hand, there was lack of space to build houses in urban areas. Blocks of "high-rise" flats seemed at first to be able to solve the problem, since they can offer more families to live in on less land. The beautiful, modem apartments in the high-rises were much sought after by people who lived downtown.
Hundreds of the vast blocks had been built before anyone began to doubt about whether they were good solutions or not. Are they suitable places for people, children especially, to live in A well-known British architect, who personally designed many of these buildings, now believes that the high-rises may well make those people who have been house
A. it was not until hundreds of the vast blocks had been built that people began to doubt whether they were good solutions or not
B. hundreds of the vast blocks had not been built until anyone began to doubt whether they were good solutions or not
C. people began to doubt whether they were good solutions or not before hundreds of the vast blocks had been built
D. since hundreds of the vast blocks had been built, some people began to doubt whether they were good solutions or not