Canada has recently stiffened its immigration rules.是什么意思？

Canada has recently stiffened its immigration rules.

加拿大最近制定了更为严格的移民规定。

Canada

n. 加拿大；

例句
Geneticists in Canada have discovered a clue to the puzzle of why our cells get old and die...
加拿大的遗传学家已经发现了解开细胞衰老、死亡之谜的线索。

has

v. 有( have的第三人称单数 )，（亲属关系中）接受，拿，买到；

例句
...the operation a patient has had.
病人做过的手术

recently

adv. 最近，近来，不久以前，近日，新近；

例句
They recently failed to negotiate a mutually acceptable new contract.
他们最近未能谈成一个双方都满意的新合同。

stiffened

n. 僵硬的；v. （使）变硬，（使）强硬（ stiffen的过去式和过去分词 ）；

例句
Ada stiffened at the sound of his voice...
埃达听到他的声音吓得人都僵住了。

its

pron. (it的所有格形式)它的，厥；

例句
The government is to accelerate its privatisation programme.
政府将加快其私有化计划的进程。

immigration

n. 移居，移民人数，移民局检查站；

例句
I am also looking forward to getting more acquainted with immigration law.
我也期待能对移民法有更多的了解。

rules

n. 规程，规章，条例，守则(rule的复数)，规则( rule的名词复数 )，统治，习惯，尺；

例句
Entries which are not in accordance with the rules will be disqualified.
不符合规定的参赛作品将被取消资格。