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Choose the right verb form.
One day in the year 1895, when the German physicist Wilhelm Konrad von Roentgen (1) ----- in his laboratory he (2) ----- that the radiation was passing through objects that were opaque to ordinary light. He named his discovery X-strahlen which (3) ---- into English as X-rays the X signifyng that the nature of the radiation (4) ---- unknown.
1. a) experimented b) is experimenting c) was experimenting d) experiments
2. a) was finding b) found c) had found d) finds
3. a) is translated b) translates c) translated d) had translated
4. a) was b) has been c) had been d) will be