板式楼梯的优缺点有哪些？
（）技術が進んだおかげで人々の寿命はむかしに比べてずいぶん延びました。 ["衣料","医療","医学","衣糧"]
The advantage of geostationary satellites is（）. ["the range of antenna can cover everywhere in the world","we can know the ship’s exact position","that the distress alert can be located as soon as possible","antenna of permanent earth stations may be directed towards fixed points in the sky"]
汉唐时期中国自中亚进口最多的商品是（）。 ["马匹","宝石","香料","玻璃器"]
The frequency（）the safety message will be transmitted shall be included in DSC safety call. ["which","on which","at which","in which"]
梁式楼梯的优缺点有哪些？
