Since all engineers are technical, it means at least some technical people must be engineers.

Since no metal is a liquid at room temperature, the statement 'Some liquids are metals' is definitely false.

Since all A are B, all B are C, and some C are not D, it follows that some A are not D (as some of C are not D).

Although some intelligent people are not ambitious, this doesn't mean they are not successful through other means.

While some knowledgeable people are not wise, we cannot determine if the non-wise ones include teachers or not.

While all fruits are nutritious, only some nutritious foods are expensive, so we cannot determine which fruits are expensive and therefore unavailable.

Although mountains are geographical features and some geographical features are tourist attractions, we cannot confirm that the mountains which are geographical features are among those that are tourist attractions.

Some healthy foods are affordable. Since all organic produce is healthy, some organic produce could be among those affordable healthy foods, hence some organic produce may not be expensive.

While all renewable sources are sustainable, only some sustainable practices are costly. We cannot establish that all renewable energy sources are among those costly practices.

Some lazy people study, and all lazy people are pessimists, and no pessimist achieves success. Therefore, some who study may not achieve success.