Consider the statement for mechanical ventilation.
A.) It is done for the long tunnel
B.) It has two methods blowing and exhausting.
C.)Combination of blowing and exhausting cannot be used just after blasting.
D.) For dust prevention vacuum hood can be used.
The true statement is\are:
1
A, B, & C
2
A, B, & D
3
B, C, & D
4
All of the above