In the sentence 'They were asked to wait "Till the signal was given ' the underlined part constitute ---

Adverbial Clause

যে clause টি verb কে modify করে তাকে Adverbial clause বলে। সাধারণত verb-কে when, where, why, how দ্বারা প্রশ্ন করলে প্রাপ্ত উত্তরটি Adverbial Clause হবে ।

 I shall go where he lives. 

Kinds of Adverbial Clauses:

A) Adverbial clause of Time

B) Adverbial clause of place

C)  Adverbial clause of Reason

D)  Adverbial clause of Manner

E) Adverbial clause of Concession

F)  Adverbial clause of Condition

G)  Adverbial clause of Comparison

H)  Adverbial clause of Degree

I)  Adverbial clause of result

J)  Adverbial clause of purpose