_____ are mounted in pairs to protect the boiler against overpressure.A.Safety valvesB.Wat

Generating tubes in waste heat boilers are finned to _____.A.reduce gas flow turbulenceB.p

In English, /ph/ and /p= / occur in different phonetic environments, they are the ______of

Vegetables are cheap______when they are in season.A．to buyB．to buy themC．buyingD．to be bou

Student journalists are taught how to be______when writing in a limited space.A．conciseB．p

Some cranes are mounted in pairs on a common platform. which can be rotated through_____.A

Because the reading _____ in most college courses are very heavy ，students should p