某事

Have an appetite for ...

有做某事的胃口、想法

A have difficulty in doing sth.

"做某事有困难"。

Have difficulty in doing sth.

在做某事上有困难

Have / find difficulty in doing sth.

做某事有困难

Have difficulty/trouble in doing sth.

做某事有困难/麻烦

Have difficulty / difficulties in doing sth .

做某事有困难

B have difficulty in doing sth.

意为"做某事有困难"。

Have difficulty / trouble in doing sth.

做某事没有困难

Have difficulty in doing sth/with sth.

毫无困难做某事

Unit 3 grade 1 Language tip have some difficulty in doing sth.

表示"做某事有困难"，difficulty 在这个结构中是不可数名词，in 有时可以省略。

According to the clear water experiment, aeration performance of the new equipment is good with high total oxygen transfer coefficient and oxygen utilization ratio.

曝气设备的动力效率在叶轮转速为120rpm～150rpm时取得最大值，此时氧利用率和充氧能力也具有较高值。

The environmental stability of that world - including its crushing pressures and icy darkness - means that some of its most famous inhabitants have survived for eons as evolutionary throwbacks, their bodies undergoing little change.

稳定的海底环境─包括能把人压扁的压力和冰冷的黑暗─意谓海底某些最知名的栖居生物已以演化返祖的样态活了万世，形体几无变化。