Sleep is divided into periods of so-called REM sleep, characterized by rapid eye movements and dreaming, and longer periods of non-REM sleep. 41 kind of sleep is at all well-understood, but REM sleep is 42 to serve some restorative function of the brain. The purpose of non-REM sleep is even more 43 . The new experiments, such as these 44 for the first time at a recent meeting of the Society for Sleep Research in Minneapolis, suggest fascinating explanations 45 of non-REM sleep.# E! ?/ M: l9 v8 Y6 S+ a
For example, it has long been known that total sleep 46 is 100 percent fatal to rats, yet, 47 examination of the dead bodies, the animals look completely normal. A research has now 48 the mystery of why the animals die. The rats 49 bacterial infections of the blood, 50 their immune systems-the self-protecting mechanism against diseases-had crashed.
+ N' \* d ^; p2 T6 J/ F( ~ 41. [A] Either [B] Neither [C] Each [D] Any/ S9 r7 F, B, t: I! I2 z# {% g
42. [A] intended [B] required [C] assumed [D] inferred
, z; s+ H7 `! N ~$ G; z& K% L q 43. [A] subtle [B] obvious [C] mysterious [D] doubtful$ _; V) q D# A: G
44. [A] maintained [B] described [C] settled [D] afforded
; r5 [% i( R. a& Y; B 45. [A] in the light [B] by virtue [C] with the exception [D] for the purpose$ e2 s b1 d8 L( l! M# K2 E. k
46. [A] reduction [B] destruction [C] deprivation [D] restriction+ y4 a$ w7 c( R' c* u5 ?1 s8 X
47. [A] upon [B] by [C] through [D] with
0 I' C* G, R8 |& j+ a9 e 48. [A] paid attention to [B] caught sight of [C] laid emphasis on [D] cast light on
% w# i5 L6 V7 p7 ^ 49. [A] develop [B] produce [C] stimulate [D] induce" R7 I9 E* q) z: d' Q( ]
50. [A] if [B] as if [C] only if [D] if only
2 w9 O( g; F/ { I 答案:BCCBD CADAB |