如图，把重物压在纸带上，当以速度v迅速抽出纸带后，重物落在水平地面的P点．若以2v的速度抽出纸带后，物体落地点在
----Has Jack finished painting the picture yet? ---- I’ve no idea. But he______ it the whole afternoon.
-- Has your friend completed his design?-- Not yet. He ________ on it last night.
She to an English program while her parents TV.
—I think the magic from Liu Qian was the best program last night. —Oh, it’s a pity. I _______ cards with my family and missed it.
—I called you several times this afternoon. Why didn’t you answer the phone? --I’m sorry. I ________ an important meeting then.
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