WHAT LED TO THE ………..( INVENT) OF THE TELEPHONE.QUESTION 4

4. - BAI KIEM TRA 1 TIET SO 1 LOP 8
BAI KIEM TRA 1 TIET SO 1 LOP 8

4. What led to the ………..( invent) of the telephone.

Question 4: Supply the correct tense for the verbs in brackets.