單項(xiàng)選擇題

Energy losses due to （） occur in every machine.

A.speed
B.friction
C.impact
D.atmosphere

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單項(xiàng)選擇題

Emulsion oils and sodium nitrite are both approved additives, but （） cannot be used if any pipes are galvanized or if soldered joints exist.

A.the latter
B.latter
C.former
D.the former

單項(xiàng)選擇題

Emulsion oils and sodium nitrite are both approved additives, but the latter cannot be used if any pipes are （） or if any soldered joints exit.

A.chromed
B.welded
C.galvanized
D.bolted