英语 单选Many difficulities have ___ as a result of the changeov

D
现在完成时的用法
现在完成时
have∕has + P.P.
用法
⑴ 与just连用,表示刚刚完成的动作或状态（just放在have∕has与P.P.之间）.
I have just had lunch.
He has just finished his homework.
⑵ 表示动作发生在过去,持续到现在,有可能延续到将来,常与since“自从…”（后面跟一点时间）for（后面跟一段时间）连用.
I have learned English since 2000.
He has lived there for 10 years.
⑶ 表示过去的动作对现在的影响.
He has lost his key.
⑷ 与最高级连用,表示“到目前为止最…”
You’re the cleverest girl that I’ve seen.
⑸ 与It∕This the first time that…连用, 表示“第一次……”
It∕This is the first time that he has learned English.
⑹ have∕has been to…曾经去过…（已经回来了）
have∕has gone to…去了…（还没回来）
I have been to Shanghai.
Tom has gone to Shanghai.
公式
⑴单数第三人称：
肯：S.三 + has + P.P. +…
否：S.三 + has not (hasn’t) + P.P. +…
肯疑：Has + S.三 + P.P. +…?
Yes, S.三 + has.
No, S.三 + hasn’t.
否疑：Hasn’t + S.三 + P.P. +…?
Yes, S.三 + has.
No, S.三 + hasn’t.

⑵其他人称：
肯：S. + have + P.P. …
否：S. + have not ( haven’t ) + P.P. …
肯疑：Have + S. + P.P. …?
Yes, S. + have.
No, S. + haven’t.
否疑：Haven’t + S. + P.P. …?
Yes, S. + have.
No, S. + haven’t.

选D
arise是
产生,出现,形成[(+from/out of)]的意思
例如：
Unexpected difficulties arose in the course of their experiment.
在他们进行实验的过程中,出现了意想不到的困难。
Between the copartners serious disagreement...

D