新编四级听力练习 第405期

Passage Two
Approximately 90% of people in the world are naturally right-handed. Why is this so, and are we born one way or the other? The answer to this question is rather complicated.
[30]In babies and young children, no single side becomes dominant until around the age of eight. At 12 weeks, babies usually use both hands equally, [29]but by 16 weeks, they mostly use the left hand for touching. [31]By 24 weeks, they have changed again and start using both hands. Then at 28 weeks, they become one-handed again, although this time it is the right hand that is used more. At 32 weeks, they start using both hands again. When they reach the age of 36 weeks, there is another change, with most babies now preferring to use the left hand. Between 40 and 44 weeks, the right hand is once again more used. At 48 weeks, babies switch to using their left hands again, and then between 52 and 56 weeks, the right hand takes over.
There are further changes still. At 80 weeks, the right hand loses control, and both are used again equally. When the young child reaches the age of two, the right hand takes over again, but between two and a half and three years, both hands are used equally. [30]Things finally become stable at around four years and stay the same until, by the age of eight, one hand is strongly dominant over the other.

Questions 29 to 31 are based on the passage you have just heard.
29. Which hand do babies use most for touching when they are at 16 weeks?
正确答案：B
解析：原文提到，婴儿16周大时，主要使用左手进行触摸，因此B正确。
30. Until how old will a child's one hand be strongly dominant over the other?
正确答案：D
解析：选项都是岁数，这些数字可能在原文中都出现过，这就要求在听录音的同时，听到每一个数字都要在旁边做笔记。原文两次提到，直到8岁时儿童的某只手才远远比另一只手占优势，故D正确。
31. What do we learn about babies' using their hands?
正确答案：B
解析：选项都是概括性的陈述，可以猜测本题需要综合全文的大意来解答。原文用很长一段话来叙述婴儿几周大的时候用双手，几周大的时候更常用单手（左手或者右手），可知婴儿在8岁以前是交替使用单、双手的，故B正确。