He didn't _____ what I read because his mind was on something else. A. hold on B. catch on C. take in D. get over 答案:C 解析: take in(=understand)理解。 hold on(打电话时)不要挂断;catch on明白(作不及物动词用),catch on to懂得,明白(作及物动词用);get over克服。
如图,△ABC是正三角形,AE⊥BC于E,则下列结论正确的是( )
①AB=AC=BC.
②∠BAC=∠ABC=∠ACB=60°.
③AE是△ABC唯一的一条对称轴.
④AE是∠BA(的平分线.