问题 选择题

下列各组顺序的排列不正确的是(    )

A.原子半径:Na<Mg<Al

B.热稳定性:HCl>H2S>PH3

C.酸性强弱:H2SiO3<H2CO3<H3PO4

D.还原性:K>Na>Lix_k

答案

答案:A

A,从元素周期律上分析,同周期元素从左往右,原子半径依次减小(除0族元素);所以A错误。

B,氢化物热稳定性随元素非金属增强而增强,非金属性有Cl>S>P,所以B正确。

C,元素最高价对应的含氧酸酸性随非金属性增强而增强(除F外),Si<C<P,所以C正确。

D,金属还原性递变规律与金属性递变规律相似,周族元素从上往下金属性依次增强,金属的还原性也是增强,所以D正确。

完形填空

At the beginning of this century, medical scientists made an interesting discovery; we are built not just of flesh and blood but also of time. They were   36   to show that we all have “a body clock”   37    us, which controls the   38   and fall of our body energies,   39   us different from one day one to the next.

The   40   of “a body clock” should not be too   41   since the lives of most living things are controlled   42   the 24 hour night-and-day cycle. We feel   43   and fall asleep at night and become   44   and energetic during the day. If the 24 hour-cycle is   45   , most people experience unpleasant   46   . For example, people who are not   47   to working at night can find that   48   of sleep causes them to   49   badly at work.

50   the daily cycle of sleeping and   51  , we also have other cycles which   52   longer than one day. Most of us would   53   that we feel good on some days and not so good on    54   ; sometimes our ideas seem to flow and at other times, they   55   do not exist.

36.A.anxious                  B.able                        C.careful                    D.proud

37.A.inside                     B.around                    C.between                  D.on

38.A.movement                     B.supply                    C.use                         D.rise

39.A.showing                 B.treating                   C.making                   D.changing

40.A.invention                B.opinion                   C.story                      D.idea

41.A.difficult                  B.exciting                  C.surprising               D.interesting

42.A.from                      B.by                          C.over                       D.during

43.A.dull                       B.tired                             C.dreamy                  D.peaceful

44.A.regular                   B.excited                   C.lively                            D.clear

45.A.disturbed                B.shortened                C.reset                       D.troubled

46.A.moments                B.feelings                  C.senses                     D.effects

47.A.prevented               B.allowed                  C.expected                 D.used

48.A.miss                      B.none                       C.lack                        D.need

49.A.perform                  B.show                      C.manage                   D.control

50.A.With                      B.As well as               C.Except                    D.Rather than

51.A.working                 B.moving                   C.living                     D.waking

52.A.repeat                     B.remain                    C.last                         D.happen

53.A.agree                      B.believe                   C.realize                   D.allow

54.A.other                      B.the other                 C.all other                  D.others

55.A.just                        B.only                       C.still                        D.yet

问答题 简答题