Module 3 The natural world 教学设计(4)
by turns轮流;
learn by heart记熟;
one by one一个接一个地;
little by little一点点地;
side by side并肩地, 并排地
(四) 连词if的用法
1. (表示条件)如果,主句用将来时,if从句用现在时表示将来
He will come if you invite him.
如果你请他,他会来的。
2. (表示虚拟)假如,要是
1)时态:可以表示过去,现在和将来的情况。它的基本特点是时态退后。
句型:条件从句 主句
一般过去时 should( would) +动词原形
If they were here, they would help you.
2)表示与过去事实相反的假设。
句型:条件从句 主句
过去完成时 should(would) have+ 过去分词
If she had worked harder, she would have succeeded.
If he had come yesterday, I should / would have told him about it.
3)表示对将来的假想
句型: 条件从句 主句
一般过去时 should+ 动词原形
were+ 不定式 would + 动词原形
should+ 动词原形
If you succeeded, everything would be all right.
If you should succeed, everything would be all right.
If you were to succeed, everything would be all right.
3. 是否 = whether 连接宾语从句
I wonder if she is ill.
不知她是否病了。
(五) 情态动词can的用法
can表示说话人的主观看法或语气。
它没有人称和数的变化,也不能单独在句子中作谓语,但它可以与其后的不带 to 的动词不定式一起构成动词性复合谓语。其基本用法如下:
1. 表示能力,常被译成“能”、“会”。例如:
Her sister can speak English. 她姐姐会讲英语。
I can sing English songs. 我会唱英语歌曲。
2. 表示请求或许可,即常被用来请求对方的许可,或表示说话人自己的许可。例如:
Can I help you? 我能帮你忙吗?
Can you go to the picnic with us tomorrow? 明天你能和我们一起去野餐吗?