如图,R1=40Ω,R2=10Ω.当开关S闭合后,通过电流表的示数为0.3A,求

题型:问答题

问题:

如图,R1=40Ω,R2=10Ω.当开关S闭合后,通过电流表的示数为0.3A,求:

①电阻R1两端的电压;

②电阻R2中的电流;

③通过电路的总电流;

④电路的总电阻.

考点:电阻的并联欧姆定律及其应用
题型:问答题

下面文章中有5个段落需要添加首句(第61~65题)。请从以下选项(A、B、C、D、E和F)中选出适合各段落的首句,并在答题纸上将该选项标号涂黑。选项中有一项是多余选项。

A. It’s bonding time.

B. It’s time for family updates.

C. It can keep kids out of trouble.

D. It offers all kinds of activities.

E. It’s healthy for the whole family.

F. It’s a chance to resolve problems.

The Importance of Family Dinnertime

Over the past few years, more and more families are making great efforts to have regular family meals because it is very important.

小题1:__________________ Kids who live in families that eat dinner together regularly are less likely to be involved in risky behaviors. According to statistics, children who don’t eat dinner with their families are 61% more likely to use alcohol, tobacco or illegal drugs. By contrast, children who eat dinner with their families every night of the week are 20% less likely to drink, smoke or use illegal drugs.

小题2:__________________ Families who eat dinner together regularly are more likely to have stronger, happier family relationships. As families struggle to find amounts of quality time together, family dinnertime provides the opportunity for both. When families hang out together and communicate, they grow strong and healthy.

小题3:_________________ Families who eat dinner together regularly can keep in touch with each others’ lives. Everyone — kids and parents alike — can keep up-to-date during your family dinnertime on what is going on with school, jobs, family life and friends.

小题4:__________________ A regular family dinnertime provides natural opportunities for planning and problem solving. Scheduling family meeting times to discuss planning, needs and problem solving can be difficult. A regular family mealtime can offer a natural solution to the challenge.

小题5:__________________ Kids are likely to receive better nutrition when eating dinner regularly with their families. A simple, but true rule applies — when kids eat with their families, they eat better. A family dinnertime means kids are more likely to eat a nutritionally balanced meal, lower in sugar and fat content, than if they prepare or purchase meals on their own.

题型:问答题

某债券的面值为C,年利率为I,采用复利支付利息,两年后到期。一投资者以P以购买,持有至债券到期,则该投资者的持有期收效率为()。

题型:问答题

写出镁条燃烧的现象及为什么在实验台上放一片石棉网?

题型:问答题

原岩应力

题型:问答题

下列程序的输出结果是( )。

main()

int a=4,b=5,c;

ifa<B)

c=a*b;printf("%d,%d,%d\n",b,a,c);

else

c=b/a;printf("%d,%d,%d\n",b,a,c);

A) 4,5,12
B) 20
C) 5,4,20
D) 12

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