Do you hear someone knocking at the door? (Someone is knocking at the door.) 有人在敲门你听见了吗?
Do you hear someone knock at the door? (Someone knocked at the door just now.) 你听见有人敲门了吗?
7. 高中阶段常见的带介词to的短语,后接-ing分词或名词。如:
admit to(承认), contribute to(捐助、贡献), get down to(着手做), give way to(让位于),keep to (坚持、遵守), lead to (导致),look forward to(期待), take to(从事), turn to (求助于), stick to(忠于、坚持), point to(指向、表明), see to (注意、处理), be used to (习惯于), devote oneself to (献身于), be equal to (胜任的、等于), be familiar to (为……熟悉)。