vanguard|vanguards

他们站在环保运动的最前沿。

They are at the ___vanguard of the environmental movement.

这些科学家是人工智能领域的先锋。

These scientists are the ___vanguards in the field of artificial intelligence.

这家初创公司在人工智能领域处于领先地位。

The startup is at the ___vanguard of artificial intelligence.