when children learn a language ,they learn the grammar as well as the words

when children learn a language ,they learn the grammar as well as the words
When children learn a language,they learn the grammar as well as the words or vocabulary. No one teaches them; children just“pick them up”.
Before babies begin to produce words,they produce sounds. Some of these sounds will remain if they occur in the language being acquired,and others will disappear. This is called the“babbling（牙牙学语）stage”.
A child does not learn the language“all at once”.The child s first utterances（言语）are one-word sentences. After a few months,the two-word stage arises. During this stage,the child puts two words together. These two-word sentences have definite patterns and express grammatical and meaningful relationships. Still later,in the telegraphic stage,the child will produce longer sentences. These longer sentences are mainly made up of content words. The child s early grammar lacks many of the rules of the adult grammar,but eventually it will become mature.
All normal children everywhere learn language. This ability is not dependent on race（种族）,social class,geography,or even intelligence. This ability is uniquely human.
31.This passage is mainly about _____. 【】
A. the difference between a child s language and an adult s
B. ways of teaching babies to talk
C. children s learning of the mother language
D. the importance of learning foreign languages
32.The phrase“pick them up”（Line2,Paragraph1）means“ _____”. 【】
A. raise them from the ground
B. learn them without much effort
C. use hands to help carry them
D. study very hard and remember them
33.During the“babbling stage”,babies_____. 【】
A. can only produce sounds
B. learn to walk steadily
C. can understand people’s talk
D. begin to produce two-word sentences