短語詞組短語back k strength 背力back -fill strength 充填體強(qiáng)度Back -part strength test 靠背強(qiáng)度測試back strength test -static-type II &III 靠背靜態(tài)強(qiáng)度測Back strength test -static-type I 靠背靜態(tài)強(qiáng)度測strength of back flow 回流強(qiáng)度FEM back -analysis from instability-strength degradation 有限元失穩(wěn) 返回 back strength