83+____=25+____ 39+____+24=____+(76+24)
24×____ =15×____ 125×5×8×2=(____×____)×(5×2)
(25+50)×4=____×4+50×____
(75×5)×____ =75×(____×2)
从方框中选择恰当的词或短语并用其正确的形式填空(每个词或短语只能用一次)。
busy; difficult; dream of; be covered live ; arrive in; be away;
row a boat; in one's fifties; out of control ; have a chat with
毛笔从水中提出,笔毛会自然收拢,其原因是____.
在桌子上