科研項目未完成時，可以使用以下英語表達：

– The project is not yet completed.
– The project has not been completed yet.
– The project is still in progress.
– The project has not been completed as expected.
– The project is facing some difficulties.
– The project has not been completed due to unforeseen circumstances.
– The project has not been completed on time.
– The project has not been completed as per the plan.

在這些表達中，“the project”是指正在進行的科研項目，“not yet completed”是指項目尚未完成， “in progress”是指項目正在進行， “un unforeseen circumstances”是指項目遇到一些不可預見的困難， “on time”是指項目按時完成， “as per the plan”是指項目按照計劃完成。