科研项目未完成时，可以使用以下英语表达：

– 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.

在这些表达中
，“the project”是指正在进行的科研项目，“not yet completed”是指项目尚未完成
， “in progress”是指项目正在进行， “un unforeseen circumstances”是指项目遇到一些不可预见的困难， “on time”是指项目按时完成， “as per the plan”是指项目按照计划完成。