Complete these sentences using the verbs in brackets in the passive voice. The first television service ________ (to open) in Britain in 1936.

The sentence requires the verb 'to open' to be in the passive voice and in the past simple tense, as the event happened in 1936.

The passive voice in the past simple tense is formed as follows: was/were + past participle (the third form of the verb).

Therefore, the correct answer is:

Answer: was opened