Which one of the following is a component of a shield for tunnelling ?

A. soft grounds
B. rock
C. self supporting grounds
D. broken grounds

A. wagon drill, churn drill, shot drill
B. wagon drill, shot drill, churn drill
C. shot drill, churn drill, wagon drill
D. churn drill, wagon drill, shot drill

(i) shot drill
(ii) diamond drill
(iii) wagon drill
(iv) churn drill
select correct answer?
A. (i) and (ii) are correct
B. (iii) and (iv) are coiTect
C. (i) and (iv) are correct
D. (ii) and (iii) are correct

A. Both A and R are true and R is the correct explanation of A
B. Both A and R are true but R is not the correct explanation of A
C. A is true but R is false
D. A is false but R is true

i) is suitable for large sized tunnels
ii) is no,’ suitable for railway or highway tunnel’s
iii) requires heavy timbers
select the correct answer?
A. only (i) is correct
B. (i) and (iii) are correct
C. (ii) and (iii) are correct
D. (i) and (ii) are correct

A. silt
B. sand
C. clay
D. gravel