1950年6月，中 * * 党召开七届三中全会，其中心任务是( ) A．迅速消灭国民党

下列关于生态系统稳定性的叙述，错误的是[ ]

A．在一块牧草地上播种杂草形成杂草地后，其抵抗力稳定性提高

B．在一块牧草地上通过管理提高某种牧草的产量后，其抵抗力稳定性提高

C．在一块牧草地上栽种乔木形成树林后，其恢复力稳定性下降

D．一块弃耕后的牧草地上形成灌木林后，其抵抗力稳定性提高

精子形成直接由

A．精原细胞有丝分裂而来

B．初级精母细胞成熟分裂而来

C．次级精母细胞成熟分裂而来

D．精子细胞分裂而来

E．精子细胞变形而来

路基除压实度指标需分层检测外，其他检查项目均在路基完成后才进行测定。( )

VI设计的不是机械的符号操作，而是以（）为内涵的生动描述。

A.MI

B.BI

C.VI

D.CI

Teach for America (TFA) was founded by Wendy Kopp in 1990. It is a non-profit organisation that recruits top-notch graduates from elite institutions and gets them to teach for two years in struggling state schools in poor areas.

I had thought the programme was about getting more high-quality teachers — but that, it appears, is a secondary benefit. “This is about enlisting the energy of our country’s future leaders in its long-term educational needs, and eliminating inequity,” Wendy explains. It’s great if “corps members”, as TFA calls its active teachers, stay in the classroom — and many do, and rise quickly through the ranks.

But the “alums”, as she calls those who have finished their two-year teaching, who don’t stay in schools often go on to lead in other fields, meaning that increasing numbers of influential people in all walks of life learn that it is possible to teach successfully in low-income communities, and just what it takes. “It means you realise that we can solve this problem.”

As she continues to talk I realise that TFA is — in the best possible sense — a cult. It has its own language (“corps members”, “alums”), recruits are instilled (“We tell them that it can be done, that we know of hundreds, thousands, of teachers attaining tremendous success”), go through an ordeal (“Everyone hits the wall in week three in the classroom”), emerge transformed by privileged knowledge (“Once you know what we know — that kids in poor urban areas can excel — you can accomplish different things”) and can never leave (alumni form a growing, and influential, network). I have not seen the same zeal when talking to those on the equivalent programme in England, Teach First., in which the missionary-style language imported from America had to be toned down, because it just didn’t suit the restrained English style. But could that favour be necessary for its success

Chester, an alum, takes me to visit three TFA corps members at a middle school in the Bronx. They are impressive young people, and their zeal is evident. Two intend to stay in teaching; both want to open charter schools. One, a Hispanic woman, is working out with a friend how to educate migrant Hispanic labourers in Texas; the other would like to open a “green” charter, but in the meantime he has accepted a job with the KIPP charter group in Newark, New Jersey.

All three are tired. Their classrooms are not much like the rest of the school where they work, and their heroic efforts are only supported by Chester and each other, not by their co-workers. “The first year was unbelievably bad,” one tells me. “So many years with low expectations meant a lot of resistance from the kids. Eventually they saw the power and the growth they were capable of.”

The author is most likely（）

A. a graduate from elite institutions

B. an education correspondent

C. a TFA teacher

D. a Teach Firster