金属环

A device,such as a looped rope,hook and eye,strap,or grommet,used to hold or fasten loose ropes, spar s,or oars in position.

环索一种类似于绳圈、钩子和线圈、皮带或金属索眼的装置，用于把松了的绳索、桅杆或桨保持或紧固在其位置上

A device,such as a looped rope,hook and eye,strap,or grommet,used to hold or fasten loose ropes,spars,or oar s in position.

环索一种类似于绳圈、钩子和线圈、皮带或金属索眼的装置，用于把松了的绳索、桅杆或桨保持或紧固在其位置上

A device,such as a looped rope ,hook and eye,strap,or grommet,used to hold or fasten loose rope s,spars,or oars in position.

环索一种类似于绳圈、钩子和线圈、皮带或金属索眼的装置，用于把松了的绳索、桅杆或桨保持或紧固在其位置上

According to the result of asymmetric Diels-Alder reaction of phenyl-sulfonyl a , P-unsaturated ketones and cyclopentadiene catalyzed by chiral Titanium catalysts and the structure of crystal, we discussed the mechanism of asymmetric Diels-Alder reaction.

根据苯磺酞基取代的a，p一不饱和酮与环戊二烯在钦手性金属催化剂存在下的不对称Diels一Alder反应的结果以及我们测得的单晶结构，初步探讨了不对称催化Die1S一Alder反应的机理。

I didn't watch TV last night, because it .

昨晚我没有看电视，因为电视机坏了。

Since this year, in a lot of villages of Beijing, TV of elevator liquid crystal was removed.

今年以来，在北京的很多小区里，电梯液晶电视被撤了下来。