The presence of stratus clouds and a d

1、In the presence of external forces，the

In the presence of external forces，the center of buoyancy of an inclined vessel is vertically aligned with the（）.Acenter of gravityBmetacenterCcenter of flotationDkeel

2、If the length of a wire is halved and

If the length of a wire is halved and the cross-sectional area is doubled, the resistance will be （）AquarteredBunchangedCdoubledDquadrupled

3、The part of a fuse that melts and open

The part of a fuse that melts and opens the circuit is made of （）.Acopper and antimonyBsteel and babbittCaluminum or beryllium alloyDzinc or an alloy of tin and lead

4、（）is a silvery cloud in the front of f

（）is a silvery cloud in the front of feathers or fibres seen high up against a blue sky.ACirrostratusBCirrusCCirrocmulusDAltostratu

5、The average of the forward and after d

The average of the forward and after drafts is the（）.Amean draftBtrue mean draftCmean of the calculated draftsDdraft at the center of flotatio

6、In the presence of an open flame or ho

In the presence of an open flame or hot surfaces, chlorinated fluorocarbon refrigerants decomposes and from （）Apetroleum crystalsBphosgene gasCwater vaporDcarbon monoxide