用铂丝蘸取氯化钠溶液在酒精灯上灼烧,火焰呈现黄色,显色原因是
Progress______ so far very good and we are sure that the work will be finished on time.
Charles was alone at home, with_______ looking after him.
It is often ______ that human beings are naturally equipped to speak.
I can’t leave. She told me that I ______ stay here until she comes back.
—— Do you mind my opening the window? It’s a bit hot in here. —— ______ , as a matter of fact