Complete these sentences using the verbs in brackets in the passive voice. A lot of TV stations ________ (to build) in 1950s and television became very popular.

The correct answer is: "were built". Here's the explanation: The sentence requires the passive voice because the TV stations are the ones being built, not doing the building themselves. Since "a lot of TV stations" is plural, the verb must be in the plural form. The sentence refers to the 1950s, so we need to use the past simple passive. Therefore, the correct form is "were built".

Answer: were built