Pahlsson pulled out a handful of small _________(carrot) and was about to throw them away.

　　解析：carrots　根据空格前面的"a handful of"可知，此处要用名词的复数形式。

　　⑥(2017·全国卷Ⅰ)This trend, which was started by the medical community (医学界) as a method of fighting heart disease, has had some unintended side________ (effect) such as overweight and heart disease - the very thing the medical community was trying to fight.

　　解析：effects　此处根据空格前面的some以及空格后面列举的两个例子"overweight and heart disease"可知，应用effect的复数形式。

　　⑦(2017·全国卷Ⅱ)In 1863 the first underground passenger railway in the world opened in London. It ran for just under seven kilometers and allowed people to avoid terrible__________ (crowd) on the roads above as they travelled to and from work.

　　解析：crowds　根据空格前面的形容词terrible可知此处填名词，crowd表示"人群"，是可数名词，前面没有不定冠词a，所以用名词的复数形式。

　　⑧(2017·全国卷Ⅰ)The instructor kept repeating the ________ (word)，"Speed up！""Slow down！""Turn left！"

　　解析：words　根据后面的举例可知，此处应用word的复数形式。

　　⑨(2016·全国卷Ⅰ)The nursery team switches him every few ________ (day) with his sister so that while one is being bottle­fed, the other is with mum - she never suspects.

　　解析：days　every few days表示"每隔几天"，此处应该使用名词的复数形式days。

　　⑩(2016·全国卷Ⅱ)Recent __________(study) show that we are far more productive at work if we take short breaks regularly.

　　解析：studies　Recent是形容词，修饰名词，"Recent _______"在句中作主语，根据谓语动词show可知，主语需要用复数形式。

不可数名词 　　

　　1．常见的不可数名词

　　一般来说，物质名词和抽象名词是不可数的，因此没有复数形式，一般也不能用a或an修饰。

　　通常只用作不可数的名词有：milk, music, homework, housework, weather, news, butter, information, bread, advice, progress, orange (橙汁), equipment, meat, fun, luggage, luck, work (工作), traffic, furniture, wealth, word (消息), room (空间), man (人类)等。

[名师指津]　word意为"消息"，room意为"空间"，man意为"人类"时通常不带任何