【单选题】请根据短文的内容,回答题。 Maglev Trains (1) A few countries are using powerful electromagnets to develop high-speed trains, calledmaglev trains. Maglev is short for magnetic levitation, which means that these tra...
【简答题】Below is a list of alloy steels:AISI52100(GCr15);T91;Superalloy;High-speed steel; 9% nickel medium-alloy steel;AISI 9260;AISI 80;AISI 321 stainless steel.Select from this list the one alloy this is ...