Question

there is thick fog outside. All trains are running late. join the pairs with conjunction

Answer 1

there is thick fog outside so, all trains are running late.

or
there is thick fog outside therefore , all trains are running late.

Answer 2

an appropriate conjunction though it was raining we went out
missing. thick fog
all premier trains from patan junction to New Delhi were running late by 10 to 13 hours due to foggy