High alloy steel components are preheated before welding for reducing

Continuous rails for Indian railways are welded by ........ Welding process.

....................... is the non-fusion method of joining dissimilar metals with metals whose melting temp is greater than $${400^ \circ }C$$.

In spot welding of aluminium sheets, the welding current should be .........A........ and weld time should be kept ............B......... than for $$MS$$ sheet of same thickness.

(A). higher / lower, (B). higher / lower