Put the verbs in brackets in the correct form of the present perfect simple or presens perfect continuous.
Scientists say they 1)............... (discover) a new wonder drug that can help people lose weight without having to diet or take exercise. They 2)................ (test) the drug on laboratory rats for the past year and say they 3)................ (have) good results. "We 4)................. (not/start) testing the drug on humans yet, but it won't be long before we do." said Professor Higgins.
Although research 5)............... (show) that there may be a market for the new wonder drug, dietician Rosemary Connors is against the idea. She says: "The only safe way to lose weight 6)....................... (always/be) a balanced diet and regular exercises."
1. have discovered
2. have been testing
3. have had
4. haven't started
5. has showed
6. has always been