第一心音的听诊特点，错误的是A．在心尖部最响B．历时较短C．音调较低钝D．与心尖搏动

下列转移性骨肿瘤特点中，哪项是错的()

A．脊柱转移最常见

B．同一原发灶，可兼有溶骨性、成骨性转移

C．可有软组织肿块或肿胀

D．膀胱癌多为成骨性转移

E．甲状腺癌转移者，局部骨可膨胀

The effects of air pollution on natural conditions have been a disturbing problem for many years. Some scientists hold the view that the air inside houses may be more dangerous than the air outside. It may even be one hundred times worse.

Most scientists agree that every modern house has some kind of indoor pollution, which can cause a person to feel tired, to suffer eye pain, headache and other problems. Believe it or not, some pollutants can cause breathing diseases of blood and even cancer.

What made us feel relieved is that there’s growing concern about the problem now. It is true that when builders began constructing houses and offices they did not want to waste energy. To do this they built buildings that prevented or limited the flow of air between inside and outside. For the same purpose, man-made building materials were employed to build houses, which are now known to let out some harmful gases.

Facing the serious challenge, scientists have been searching for a way to handle the problem. To everyone’s delight, they discovered a natural pollution control system for building—green plants, though they do not really know how plants control air pollution. Scientists suppose that a plant’s leaves absorb or take in the pollutants and in exchange gives out oxygen through its leaves and tiny organizations on its roots. Therefore they recommend that all buildings should have one large plant or several small plants inside for every nine square meters of space. Because studies indicate that different plants absorb different chemicals, the most effective way to clean the air is to use different kinds of plants. In conclusion, having green plants inside your house can make it a prettier and healthier place. Why not try?

小题1:Which of the following statements is TRUR?

A．Outside air pollution is more harmful than the air inside.

B．Scientists have discovered how plants control air pollution

C．Indoor air pollution may cause diseases including cancer.

D．Only large plants can absorb harmful gases indoors.小题2:According to scientists, some kind of indoor pollution can be found in ________.

A．every old building

B．every modern house

C．all kinds of houses

D．all kinds of offices小题3:What does the underlined part “To do this” refer to in Para3?

A．To build houses and offices

B．To limit the air flow inside

C．To use man-made materials

D．In order not to waste energy小题4:The reason why we should use different kinds of plants to clean the air is that ___.

A．plants can drive out all kinds of pollutants indoors

B．plants can absorb different harmful indoor chemical

C．plants can take in all pollutants inside and outside

D．plants may give out more oxygen than people need

乳糖操纵子的作用机制？简述乳糖操纵子的结构及其正、负调控机制

电力安全事故发生后应如何处理？

被测对象的公差值越大，对计量器具的（）要求越低

A、灵敏度

B、准确度

C、平行度

D、平面度