You have to study the nutsandbolt of english grammar.
你必须研读英文文法的基本细节。
2
The high-strength right-screwing threaded steel bolt is formed by full thread reinforcing bars and cast steel nuts.
一种高强度右旋螺纹钢锚杆，是由全螺纹钢筋和铸钢螺母构成。
3
According to user requirements or to map, like the production of tough, high strength, large bolt, shaped bolts, nutsand various shaped pieces of shaped and non-standard items.