The answer is a combination of consumer psychology and opportunistic retailers and card issuers.

an opportunistic infection

机会性感染

TB occurs earlier in the course of HIV infection than many other opportunistic infections.

与许多其他机会感染相比,结核病在HIV感染过程中出现较早.

In some instances, patients develop opportunistic infections during this early phase of infection.

在某些时候, 病人在感染初期会有机会感染的可能.

To probe the manifestations of opportunistic infections in AIDS patients to improve knowledge of AIDS.

目的探讨艾滋病(AIDS)患者机会性感染的临床表现,提高对该病的认识.

His move was characteristically opportunistic and had fatal consequences.

他这个行动带有铤而走险的味道,其后果是悲惨的.

These vacillating elements are opportunistic.

这种动摇就是机会主义.

Procurement section only lists opportunistic infection drugs without specifying which drugs.

采购部分只说明有治疗机会性感染的药物,但并没有说明是什么药物.

The product include software guard system , this guard system has alarm system, which prevent opportunistic behaviors.

具备软件监视系统,钓鱼停机,并有警铃装置, 安全可靠.

Once again , opportunistic Imperial warlords pounced.

善于投机的帝国军阀再度崛起.

AIDS, the last stage of HIV infection, is defined the appearance of potentially lethal opportunistic infections.

hiv病毒感染的最后阶段即爱滋病, 其定义就是出现有潜在致命可能的感染.

I have an interesting, well-paid job, with opportunities to travel.

我的工作很有趣，薪水又高，而且有很多旅行的机会。

They intend to close the school at the earliest opportunity (= as soon as possible) .

他们打算尽早关闭学校。

There was no opportunity for further discussion.

没有机会进行深入讨论了。

The best reason for a trip to London is the super opportunity for shopping...

绝佳的购物机会是前往伦敦的最好理由。

At least give him the opportunity of explaining what happened.

至少要给他机会解释一下发生了什么事。

a window of opportunity (= a period of time when the circumstances are right for doing sth)

行事的良机

I had an opportunity to go to New York and study...

我曾经有一个去纽约学习的机会。

He is rude to me at every opportunity (= whenever possible) .

他动不动就对我粗鲁无礼。

career/employment/job opportunities

职业发展 / 就业 / 工作机会

The opportunity has not yet arrived.

时机尚未成熟.