话题 one friend of mine

话题 an item of clothing

话题 an item of clothes

话题 in both of which

话题 ahead of my time

话题 get in out of

话题 amount of 后接复数名词

话题 pay out of pocket

话题 be out of sth

话题 be short of sth

话题 be ashamed of doing

话题 cheat sb of sth

话题 in and of itself

问题 这里是否少了一个冠词

... after doctors completed a 20-hour operation _______ one-year-old twins at the head.A. to separate B. to have separated 老师，您好。题目中one-year-old twins到底指多少对双胞胎？和语境融洽吗？如果不融洽，应该如何修改呢？您的看法是什么？为什么？

问题 现在分词作结果状语时逻辑主语问题

Public infrustructure did not keep pace with urban sprawl, causing massive congestion problems. 一般说来，过去分词做状语，其逻辑主语应该就是主句的主语。但是我觉得这里 causing 的主语是前面整句话。这可不可以理解成分词做定语省了 which is...