Example Peter noticed something. There were nine golf balls in the river. (that) Peter noticed that there were nine golf balls in the river.
Example Something worried the climbers. The odd light meant something. (what) What the odd light meant worried the climbers.
Example Some of the engines were scheduled to be scrapped this year. The saboteurs have demolished the engines. (which) Some of the engines which the saboteurs have demolished were scheduled to be scrapped this year.
Example The girl suddenly began to scream in terror. The girl was walking through the park. The girl walking through the park suddenly began to scream in terror.____________________