Is this sentence correct, which I want to express that all praising expressions were spoken in a fast way.
Praising expressions were spoken with a relatively fast speaking rate.
Is this sentence correct, which I want to express that all praising expressions were spoken in a fast way.
Praising expressions were spoken with a relatively fast speaking rate.
Although your sentence is not idiomatic, it is grammatically correct. The modifying clause with a relatively fast speaking rate is adverbial, and the question of agreement-in-number with the verb does not arise.