_____ many times, but he still couldn't understand it.
Mike didn’t notice Alice entering his room. He ____ a phone call.
—Did you find the missing couple in the mountain yesterday? —No, but we ________ to get in touch with them ever since.
—Such a mistake could have been avoided. —Unfortunately, he _______ the mistake again and again.
—May I remind you that a Mr. Wang is waiting outside, sir? —Oh, that’s right. I __________ about it.
—Did you enjoy your holiday? —Yes, it’s the best holiday I ___________ these years.