23592U和23892U是铀的两种主要的同位素。U是制造原子弹和核反应堆的主要原料。下列有关说法正确的是
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
It’s high time you had your hair cut ; it’s getting _______ .
My friend showed me round the town, ______ was very kind of him.
They use computers to keep the traffic _______ smoothly.