The research is so designed that once ______ nothing can be
| The research is so designed that once ______ nothing can be done to change it. |
| [ ] |
| A. begins B. having begun C. beginning D. begun |
可能相似的问题
你能帮帮他们吗
| The research is so designed that once ______ nothing can be done to change it. |
| [ ] |
| A. begins B. having begun C. beginning D. begun |
你能帮帮他们吗