Roses will always have thorns but with care they can be avoided.

玫瑰花上都有刺，不過只要小心就碰不到。

...the shade of a thorn bush.

一叢荊棘下的陰涼

...the thorn and bramble thickets.

荊棘密布的灌木叢

She's a real thorn in his side.

她真叫他頭疼。

The Party was a thorn in the flesh of his coalition.

該黨是他所在聯盟的眼中釘、肉中刺。